DPS definately had the easiest job in wotlk, i wouldn't say they have the easiest job now, infact, they've probably got the most to learn...
Tanks, well, pretty much no change there, even the wrath tanks that pulled half an instance mostly knew their limits, and should realis on their very 1st cata hc pull that this has changed.
Healers, other than having tom completely re-learn their healing strategies, no change (andmitedly, re-learning you class is a pretty big change though..)
DPS - now have to learn what cc is, learn what raid markers are, learn that aoe is not always king, learn to use stuns/silences/interrupts on cooldown, can't stand in the fire any more - Yes, this should be fairly easy, but sooo many dps are still using all their bad habits from wrath.
Healing is really harsh to get into now, healers can go oom very quickly, and then have the dps on their back moaning that they ain't good healers. To be honest, the worst dps I've seen are the ones that don't know what CC is or just stand around during most of the fights when they are needed.
Also I've seen some atrocious lack of dps in hc dungeons (players barely hitting above 4k), it makes taking down Cindy without any tactics for phase 2 look easy in comparison, which reminds me, maybe I'll go back and get my bane title.



