In PVE I really like my shamans. I think most teams who cleared heroics did it with Shamans in the group. I used 4x shamans and 1x druid tank. They aren't the best DPS, but if you do the macros right, they really do good dps. The better gear you have, the less mana issues you have. They scale very well at the higher end, with crap gear the suck, but when they start getting geared, they get to a point where mana isn't an issue, and do solid dps. Plus they can heal without changing forms, which really is a life saver.