For the most part Paladin and Gunbreaker so far from my experience feel good to play and definately feel fine given the amount of concentration you need to be optimal on them.

I can't speak for DRK since I haven't touched DRK since expansion.

WAR on the otherhand... BOY did they dumb down that job. I actually fell asleep at my monitor while doing Titania EX as WAR once, my god did they not realize WAR dumbed down too far from SB. There is just so little to do as a WAR until IR comes off cooldown then you finally have 10 secs where you feel like you are impacting and need to somewhat concentrate so you don't botch it up. After that you enter a down period that just feels bad to play honestly.