I haven't really sat down and given much time yet, but my playing my priest just feels so disconnected to how I remember it. Not sure if I just need more playtime to get back into it and adjust, but I was honestly finding it hard to get going. On the plus side I think I'm finally happy with the UI side of things now I've had a tinker. Think I may just grind this priest through to 120 so I can get started on the dungeon and raiding aspect of the game again with a couple of mates that are more into it than the rest, and then level a new character to actually follow the story / lore again as I have no clue as to what's going on!
If you're struggling maybe try getting a TellMeWhen profile from http://www.chesder.com/wow.html.
He has all classes available. Basically tells you the best spell to use next in your rotation; works with all specs too. Very easy to set-up too.