Spriests are doing a little too good right now. With the patch that came out on Tuesday (3.0.3), they made it so that while in Shadowform, your DoTs are increased by a percentage equal to your crit chance. This, along with a couple other minor changes has allowed Spriests to be a bit OP.
I was at the top of the DPS in Kara, Mag's, and Gruul's the other night, and I have to admit, it was perfect. Spriest plays just like I want it too. Sure, I could use a bit more mana, like how the old VT worked, but playing a Spriest just seems more exciting to me.
Shadow Word: Death phails now - no complaint there. VT is a good DoT now, Devouring Plague is usable on my Blood Elf, and the Mindlfay graphic looks like someone dumped the old one into Illidan's Epic Blender of Awesomeness from the Black Temple kitchen and pressed "PWN".
tl;dr version: Play your spriest. I iz happy with the class.
Until Blizz decides we're having too much fun and hits us with the Nerfbat...