Yes, I know that I'm a bit late but I wanted to actually play around with the changes for a bit first to make sure that I knew what I was talking about.
In PvE, the general consensus seems to be that holy got a big, fat buff this patch. I think part of that is actually just the fact that unlike Firelands, Dragon Soul seems to be shaping up to be very "holy-friendly", but more than anything else PvE holy priests have been boosted by the buff to Divine Hymn.
Unfortunately this does very little in PvP, where interrupts are so prevalent that you're lucky if you can get a Flash Heal off. Channelling a spell for over seven seconds? Get real. There are exactly two occasions in PvP where I do use Divine Hymn: One, when I'm already dead, in Spirit of Redemption form and thus safe from interrupts, and there are lots of people around me who need heals. This doesn't tend to happen more than once a game, so it's not really worth investing extra talent points into it. Two, when High Commander Halford Wyrmbane in Isle of Conquest does his crushing leap and most of the raid inevitably fails to avoid it and gets hurt really badly. Yeah, not really worth spending points on either.
Still, holy has been buffed for PvP this patch, via the reduction of Holy Word: Serenity's cooldown. I hit that baby pretty much every time it's off cooldown, and I used to attempt to hit it when it was still on cooldown as well. Actually, that still happens even now, but less so than it used to. More instant healing? Yes, please!
On a side note, the patch notes also state that the developers reworked the functionality of Spirit of Redemption, presumably to address issues such as people not getting achievement credit for some things while in spirit form. Good plan, but in PvP this has apparently resulted in a bug that causes our deaths to never show up on the score board at all. It's silly, but I actually get a bit of a kick out of it. Oh really, you killed me five times? Well, you can't prove it! Zero deaths, see? I'm invincible! The thing that would really interest me is whether it's just a display bug or whether it actually affects the death counter on a functional level, as that would mean that holy priests could now potentially "cheat" their way towards getting achievements that require you to do certain things without dying (such as Ironman). I haven't really tried it.
Also, one stealthy change that wasn't mentioned in the patch notes is that they changed the Levitate animation so that when you run while levitating, your legs don't move anymore and you just float. I cast it on our warrior in Arathi Basin and he spent the next minute floating around the Stables flag going: "Boo, I'm a ghost!" Now that is clearly broken.