[Cheesegear]

With all this talk of Space Wolves...Let's do this...
The FAQ is pretty much required reading. As it clears up a lot of things, and, in some cases, actually changes how some units are used.

Special Rules:

Spoiler

Right, first off, Space Wolves lose Combat Tactics and Combat Squads. Combat Squads you can do without. Combat Tactics is a bit of a loss, but, instead you get Counter-Attack on everyone. Which enables you to play a lot more defensively and not actually lose anything for it.
This is way better than the Red Thirst of the Blood Angels! But, not quite as good as Black Templars' bizarre Morale check-Fearless rules.

Acute Senses is a bonus. You could do without it. But, hey...Whatever. You've got Counter-Attack.

ATSKNF. Like all Space Marines. Still, without Combat Tactics to synergise it's less good. So? You've got Counter-Attack.

HQ* - The Leaders of the Pack
First, this rule allows you to take 2 HQ choices for every one FO Slot! Second, it means that your characters must all be armed differently. Normally, this isn't a problem as Rune Priests come with Force Weapons and Wolf Priests have Crozius Arcanums automatically making them separate to anything else you can field.

Problems arise when you want to stack Characters though. However, the FAQ states that a set of Melta Bombs or an extra Fenrisian Wolf solves the issue. Just so long as one thing is different. Although it's Not Cool to skirt the fluff like that.
You can also have all four Rune Priests with Living Lightning, so long as they each have a different secondary power.

As Wolf Guard (not the Battle Leader) are not HQ*, and are rather Elites, you do not have to arm them differently. Secondly, Daemonhunter and Witch Hunter allies also are not HQ*, and are actually regular HQ, and, as such, take up a whole slot instead of 'half'.

Wargear:

Spoiler

No access to Relic Blades, Hellfire Rounds or Axillary Grenade Launchers.

Iron Halos (Belts of Russ) aren't free.
Storm Shields cost more points (as they should).

Frost Weapons: Grant +1 Strength (rather than the +2 of Relic Blades). However, they also count as Power Weapons, and so can be combined with a Pistol for +1 attack. Nice.

Wolf Claws: Like Lightning Claws, but better. However, to use them properly you need a pretty good knowledge of the game to see whether you want to re-roll To Hit or To Wound. If you have multiple models in the same unit with Wolf Claws, you can actually pick and choose who is doing what. Thier points cost is only slightly higher than Lightning Claws.

Terminators can't Teleport.

Fenrisian Wolves: Most treat them as ablative wounds with attacks. Or a way to get around Leaders of the Pack without wasting too many points.
Mark of the Wulfen: Don't give this to Independent Characters. They've got better things to do.
Thunderwolf Mount: Happy Face. Good luck trying to model one though. Sad Face.
Wolf Tail Talisman: Not only do SWs already have Psychic Hoods, but, now they can also disrupt psychic powers without the help of a Rune Priest.

Wolftooth Necklace: Nice. Goes very well with the right Wargear. Like Wolf Claws and/or Beastslayer (below).

Wolf Standard: Hit or miss. But, it's only 10 points and you can have it on Troops units.

Sagas:
No two characters can have the same Saga. Except for special characters.

Wolfkin: Crap. Don't worry about it.
Bear: Happy Face. Put this on your favourite guy. Add a Storm Shield.
Majesty: Meh.
Hunter: Allows your guy to hang out with Wolf Scouts, not much else. Add a Thunderwolf Mount where possible.
Warrior Born: It stacks. Keep on rollin'...Just don't screw it up. It's points cost really does reflect how good it can be.
Beastslayer: All To Hit rolls. Including those from Shooting attacks. Makes some of the better models in the game, less good. It's a shame that you can't combine this with Bear which you kind of do need.
Iron Wolf: Iron Priests only. Still pretty bad.

The List:

Spoiler

Wolf Lord
4 attacks. With Counter-Attack.
Belts of Russ aren't free.
Beastslayer, Majesty, Wolfkin, Warrior Born, Bear

Rune Priest
Rune Weapons turn Daemons to crap. The Avatar doesn't even have Eternal Warrior. Force Weapon time! Rune Weapons are also like Psychic Hoods, but slightly worse.
Chooser of the Slain: Put it somewhere awesome so enemy Infiltrators can't take that spot (like an objective), and/or put it somewhere where it can see everything.
Beastslayer, Warrior Born

Thunderclap: Nothing to write home about.
Living Lighting: Tell your friends! Add Saga of the Beastslayer.
Storm Caller: Meh. You don't really need it.
Tempest's Wrath: It's almost like Rune Priests hate Chaos Daemons...
Fury of the Wolf Spirits: Meh.
Muderous Hurricane: Screws over your opponent whether you cause casualties or not.
Jaws of the World Wolf: Not really that good. Screws over gun 'lines' if you get the right angle and Carnifii. Not too much else. Doesn't even work on Walkers or Vehicles.

...All the good ones are Shooting attacks, so you can only use one per turn. Living Lightning and Murderous Hurricane are the favourites.

Wolf Priests
Like a Chaplain. Except gives Preferred Enemy against a single unit type ('Infantry' will still hit roughly 85% of everything in the game). However, note that a Chaplain's ability only works on the turn that they Assault. Wheras Preferred Enemy works all the time. And Space Wolves have Counter-Attack on a Wolf Priest's Leadership 10? Who needs to initiate Assault? Not Space Wolves.
Beastslayer, Hunter, Wolfkin, Warrior Born

Wolf Guard Battle Leader
Like a Wolf Lord, but cheaper. And still has an awesome stat-line. WS5 and 3 Attacks.
Only difference for wargear is no access to a Belt of Russ and different Sagas.
Beastslayer, Hunter, Wolfkin, Warrior Born

Wolf Guard Pack
Not as good as Sternguard. But, also only 18 points each. 2 Attacks each plus Counter-Attack. As the 'Veteran' unit, they can take pretty much any weapon they want.
Also, a cheap source of Terminators;
Power Weapon and Storm Bolter = 33 Points
Wolf Claw and Storm Bolter = 38 Points
Power Fist and Storm Bolter = 43 Points. Meh. You're paying the same points as Dark Angels and a smart Black Templar player. You've still got Counter-Attack.
Dual Wolf Claws = 48 Points.
Thunder Hammer and Storm Shield = 63 Points. Each.

This author has seen Power Fist and/or Wolf Claw and Storm Shield combos used to great effect. Assault Cannon and Storm Shield can be mean.

Space Wolves also don't have squad sergeants like just about every other army. Instead, Wolf Guard actually get 'split off' from the main pack to join other Packs as Sergeants. It's a fairly neat rule. Except, you still need a minimum of 3 Wolf Guard even if you just want one to use as a Sergeant.

Dreadnought
Assault Cannon as the base weapon.
Can take funky Space Wolf gear.

Venerable Dreadnought
Assault Cannon as the base weapon.
Can take funky Space Wolf gear. Including Majesty so you can take the better Sagas on your Wolf Lord.

No Ironclads.

Iron Priest
Free Thunder Hammer.

Wolf Scouts
Space Wolf Scouts are actually Elites (just like in the real world) and have the Stat-line to match. Wolf Scouts also have access to Assault weapons like the Meltagun or Plasmagun. As well as also have a really cool rule which allows them to come onto the board from your opponent's table edge.
Sniper Rifles cost points.

Lone Wolf
Has both Bear and Beastslayer Sagas (but he doesn't really, so your HQs can still have them). Which is exactly what you want. Strap on Terminator Armour and a Storm Shield and he wont die anytime soon. Problem is that he's not an Independent Character, and using a whole Elites slot for just one model just isn't the best idea.
He's also missing access to a Jump Pack, Bike or Thunderwolf Mount. Which would be really handy.

Grey Hunters
Like a Tactical Squad, but can't take Heavy weapons. But can take dual Assault weapons instead. And, even though they don't have access to a Sergeant, they can still have a Power Fist/Weapon anyway. And then a separate character with the Mark of the Wulfen, and then add in another Wolf Guard. Oh, and Grey Hunters also have Combat Weapons and Pistols for another attack. And Counter-Attack.
Grey Hunters also have access to Wolf Standards. Take it or leave it.

Because of the fact that Grey Hunters can't take Heavy weapons, and the fact that they have Counter-Attack as well, they make ideal Drop Pod units.

Problem; Space Wolf Drop Pods only carry 10 models. It means you can take 10 GHs and get the two special weapons (Flamers or Meltaguns usually)...Or take 9, and the Wolf Guard, and only one special weapon because you don't have 10 models...Just keep in mind that Wolf Guard get Power Weapons and Fists for cheaper than Grey Hunters (but not really, because you lose the free second Assault weapon)...It all depends on what you want.

Blood Claws
Blood Claws can't shoot at all if they're within 6" of an enemy unit, and then, they must Assault that unit. Clever opponents will put a Land Raider in front of them.
Blood Claws can come in squads of up to 15. But, you should also know that putting a Wolf Guard in the squad means they can shoot and not-Assault like normal people.
...Blood Claws are not a Defensive unit. They're much better on the Assault rather than Counter-Attacking. Stick them in a Land Raider to near-guarantee to get them where you want them to be.

Thunderwolf Cavalry
The best unit in the List. 12" Assault Move. S/T 5 and two Wounds each and all 5 of their Attacks are Rending. Strap on a Storm Shield and watch them win. Who cares if they're 80 Points per model. They will win.

Trouble is, there is no easy way to make them. Best and easiest way is to buy multiple Canis Wolfborn models and go crazy with a saw. This is crazily expensive. But, it seriously is the best unit in the Army.

Swiftclaw Biker Pack
Like Blood Claws, but on Bikes for Relentless Twin-Linked Bolters and T4(5). Bikes they'll be able to Assault what they want to Assault. Or get a Wolf Guard.
Cheap Attack Bikes.

Skyclaw Assault Pack
Like Blood Claws, but with Jump Packs. Add Wolf Guard.

Fenrisian Wolves
Wolves. On the Battlefield. They have the statline of a Space Marine, except with 2 Attacks each and terrible Leadership and save. Still, they're really cheap and have 12" Assault move.

Long Fangs
Due to the fact that no other squad can take Heavy Weapons, these guys can take five of them. And then, split their fire between two targets at the same time. The unit gets expensive if you're not careful.

Land Raider
Only carries 10 models.

No Thunderfire Cannons.

Drop Pod
Only carries 10 models. No Locator Beacons.

Bjorn the Fell-Handed
A Special Character Dreadnought.
He has a 5+ Invulnerable. On a vehicle...Very overpoints'd though.
If he dies, he counts as another objective. This can be used to turn a losing game into a draw.

Ulrik the Slayer
He's pretty good.

Arjac Rockfist - Wolf Guard upgrade
He's a beast. Almost as good as Lysander, except without enough wounds.
A tad overpriced.

Lukas the Trickster - Blood Claw upgrade
LOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOL!!!!1!! !111!!!!11!!
That is all.

Njal Stormcaller

Canis Wolfborn
Kills Infantry dead. Sadly, he has no Invulnerable and no Eternal Warrior. Stay away from pie plates.

Ragnar Blackmane
He's quite good.

Logan Grimnar
He's a pretty funky dude. And turns your Wolf Guard into Troops. Some people have been using him to field Terminator armies because Space Wolves get cheaper Terminators. Pfft. Logan Grimnar costs a truckload more than Belial. You need to take at least 21 non-upgraded () Wolf Guard Terminators just to break even. Non-upgraded.

TL;DR: Final Thoughts

Spoiler

Space Wolves are actually the 'most fair' list out of all the Space Marine variants. Specialising in medium-range firefights and defensive deployments. They're still plenty good in Assault because they all have Counter-Attack and Grey Hunters (the basic Troop) rock like a Ducati.

You can't Rifle spam.
You can't Hammernator spam.
You can't Land Raider spam.
You can't Thunderfire spam.

Well, you can do some of those things, it just doesn't work as well as other Space Marine Lists.

Ultimately, Space Wolves are a solid list. They have no actual 'bad' or 'trap' units. You can even make Fenrisian Wolves work if you try. The only way to 'break' the List is to Thunderwolf Spam, and that's out simply because they're so damn hard and/or expensive to make.

The other thing Space Wolves have going for them, is that their rules actually conform to their fluff.