I'm using a staff as my mesmer right now. Not sure if it's better than Sceptre + Focus, really. I've played too little to be able to tell. The basic sceptre attack seems better at placing clones close to the enemy so you can blow them up, though.
I didn't even bother with shatters on mine during beta.
I used sword/pistol [for ridiculous melee DPS and a little survivability] and greatsword for ranged.
Instead of using clones for shatters, I used phantasms for DPS.
It was quite fun, and was actually one of my favorite beta toons.