THe only one that really leapt out at me was the Warlock. in all, I like the other classes. But Warlock? No thanks.
They don't get an implement right away, and that means they're going to miss more often than most at low levels. Even now, at 5th level, our Warlock seems to miss a lot.
Damage is only so-so, though our Darklock can deal a fair amount of damage late in the fight using his Dark Pact power.
They do require you to move about on the battlefield, which is fun... but I find that, as an archer, there are many times when you just need to sit still.
I'm not a huge fan of the angsty flavour. I know, it's changeable, but as written, I don't really like it.
The other classes are fine in my book. I like the fighter, for the most part, though he can be annoying if you're the GM. The Paladin seems a bit weird regarding marking, and Lay on Hands is sort of weirdly written, but the class works. The Warlord is AWESOME, and if I played, it'd be the first class I'd consider. The Cleric seems like a lot of fun to play. The Ranger is a huge damage dealer, and I'd almost consider it broken after seeing one in play... but once he got stuck in close range combat, I realized how easily he can fall.