questions about mop before joining

I plan on playing MoP and I'm already stocking up on coins and vps but first I want to know a few things:

I always play warrior in every expansion, it's my main class, but this time I want to start something different. I was planning to join as a shadow priest, but first I want to know its state in pvp: is it viable? Do key talents work? Is it all around a good spec like in wotlk or does it suck ***? Also, does glyph of sha work at all? I was charmed by its orrific appearance and so I wanted to make a spriest and run around with that ugly thing.

Any other thing I should be wary of? Like, very common known bugs, or the current state of the realm? I heard everyone rolls warrior

thank you

spriest top bg dmg chart

hi there

shadow priest in mop re in a nice place. They do great in both pvp and pve.
unfortunately one nice pvp talent (HALO) is totally not working. the rest are working.

for bugs about priest there is bugtracker! :)
Everyone rolls warr because is stupidly bugged in positive. Is a noob friend class and easy to understand. Server is already FULL of human warriors and tauren warriors/orc warriors so no, for the sake of god roll priest.