Yeah, I know I'm a little late to the expansion, but I stopped playing back in 4.3 and recently regained interest in WoW.
I've heard people say that Holy is "useless" and that Disc is much better...this true? I've always been a Holy guy, myself; always enjoyed its huge AoE heals and versatility over Disc, tbh, but if Disc is better, I'll play it. (Kinda like patch 4.2 when Holy was shit compared to Disc because its cooldown sucked and its mana regen was atrocious compared to Disc's)
No real rush; I don't even have full MoP on my account yet (just the trial, waiting for copy of MoP to arrive on Thursday) but I've started the leveling process on my Priest at least. (it let me get to 8,699,999 / 8,700,000 exp, can't get to level 86 though!)