I feel like there wasn't enough differentiation between some of the classes, and that they deserved more than a single unique power.
Also, if you look at things like how Sentinel was presented in ME1, where it's supposed to be possibly the weakest class and away from the front line where you're constantly slinging powers, and how that class was in ME2 and ME3, where the armor meant you were rushing in and then you get cooldown penalties to using your powers...
Wasn't there a bug in ME2 where the armor going off reset your cooldowns everytime?
I imagine once again the Vanguard is going to be the most fun to play because of the jetpack combos.