edit: I will say though, healing is much more difficult in Cataclysm, to the point where it's going to be an acquired taste like tanking (I say that because there are so many shitty healers out there who just get by). The amount of damage throughput in some of these dungeons and heroics is pretty amazing, and while you have the toolbox to deal with it, it's stressful. You have to get used to people not being topped off, which isn't something that really existed in wrath. Also, a lot of the burden shifts onto the dps. There are a lot of enemy abilities that will just automatically kill them if they are playing sloppily, and there is nothing the healer can do about it.