In depth critique of things minor and major:
  • From a flavor standpoint, not a huge fan of the flavor text provided above the class details. I recognize that disconnecting from the standard age = size category to class level = size category is a bit weird, but as is, it kind of jibes with the notion of playing a regular ol' silver dragon. I suggest letting people come up with their own explanations, or offering a few in the flavor text if need be.
  • Your attacks at level one are kind of overwhelming. As many as a common housecat! Only where the dreaded housecat has size bonuses, you've got full BAB and bigger damage die. So you're full attacking for a potential 24 damage at a point when most foes will have around 10 hp.
  • Alternate form may be abusable. I'd be hard pressed to name exactly how, but there's a distinct disconnect between CR and HD. I'm sure there's some animal/humanoid forms with low HD but potent racial bonuses/effects.
  • You've got inconsistent usage of Silver Dragon (capitalized) and silver dragon (no caps). A case sensitive find & replace will fix that.
  • Draconic Roar - I would say that if you're halving the damage already, it would make more sense to just negate it if the surrounding foes make their Reflex save, as opposed to quartering it if they do.
  • Just curious what your line of thinking was on the ability scores. They're kind of sporadic until a certain point, where they come in very consistently. What was the aim?
  • Silver Ingenuity should perhaps be "At level 4 the silver dragon gains 4 additional skill points, and gains 1 additional skill point for every HD it has after the first, and every HD it acquires thereafter." as the current wording of 'applied retroactively' can create awkward situations/vagueness.
  • Under silver resistances, should be 'gains immunity to cold and electricity resistance...'
  • Boon of Bahamut needs to state that it's a touch skill and a standard action.
  • Domain - I'd suggest clarifying to "Chooses one domain from the following:"
  • Domain - also, I'd clarify to "you do not get the granted power of any chosen domains." - as read, it could be interpreted as referring to the storm domain.
  • The paladin spellcasting is confusing. Is it retroactive? Maybe refer to it as "spellcasting of a paladin X levels lower than him?"
  • Minor flavor issue with Improved Alternate Form - is there really any reason for a dragon to not just be in a special form 24/7 for the racial bonuses/features/abilities?
  • Silver Will is a bit over the top for the level you get it. It's basically mind blank (an 8th level spell) at level 14.
  • Frightful presence - I'd suggest allowing the Silver Dragon to turn it off.
  • Protective Aura - A +4 to all saves for all allies at level 16 is pretty major. This, if anything, should be a capstone.
  • Same issue with Bahamut's Grace. Huge bonus to saves is huge (only here it's a potential +6 to +8)
  • Lightning Breath - the range thing needs to be clarified. I can't fathom the intention.


Scoring:
Originality: I like the direction that you've taken as far as trying to conceptualize the dragon in a specific role, but worry that you're running in parallel with the paladin. In many respects, it is a better paladin dressed up in a dragon's body. 3/5.

Balance: Some issues with specific abilities (Silver Will, Bahamut's Grace), potential shenanigans with alternate form (improved or otherwise) and with a little too much power at early levels. That said, I do think you're more or less on the right track if you're aiming for a tier 2-3 level. 3/5

Flavor: It fits with what a silver dragon is. Nothing here, beyond the potential for a silver dragon to use an alternate form 24/7, that really jibes with the flavor or would make me raise an eyebrow if I saw a silver dragon use it in a game. 4.5/5

Elegance: Several abilities missing details (such as what action type & range boon of bahamut is) and vagueness or potential misunderstandings in some areas (like Silver Ingenuity and domain. I think the Ex, Su, etc, should be bracketed as it makes reading the ability names a bit mucky, and there's the inconsistent Silver Dragon vs. silver dragon at points in the text. 2.5/5.

Playability: It's actually pretty darn playable as is, which earns a thumbs up, but as mentioned just above, there's vagueness that would lead to DMs having to adjudicate how an ability works on the fly or causing potential misunderstandings and arguments. 3.5/5.
I recommend Kyuubi contact me as changes are made - I have no problem adjusting my scores to reflect adjustments and fixes.