The priest class got a major talent overhaul with the talent expansion. Many priests feel like they were jypped. Initially i felt the same way. But after delving into the new talent tree and researching the forums I found that what blizzard did was realign the class with their original intent. Spirit plays a much more important role and the discipline tree is now actually functional for priests over 45. The shadow tree didn't see a lot of improvement and it really didn't need much. The holy tree is still very specific to high lvl raiding priests when it is the primary tree, and that is probably as it should be. The holy tree should still be considerred a s a point dump though since there are some good talents in it especially healing focus. Regarding the endtalents, none seem too important and most of the best talents seem to be below 36 points in any one tree.
Good Luck Preists and please contribute to this discussion so we can generate new ideas.
I recommend reading as many of the priest forums as possible but these two have some of the best info:
Tarana's Guide to All The Nagging Questions
http://forums.worldofwarcraft.com/thread.html;jsessionid=CDC6A8DA8438B0F2DA15D96FD138B9A2?topicId=12052926&sid=1The Priest Mana Regeneration Model
http://forums.worldofwarcraft.com/thread.html;jsessionid=CDC6A8DA8438B0F2DA15D96FD138B9A2?topicId=11893046&sid=1