Disclaimer Unfortunately, I can't go over every single PvP change. I'm going to try to hit lots of the important ones. "Important" is, of course, a subjective word. You might disagree with the selections I have made -- you might think they're not very important or that I left out ones far more important. That's okay; leave a comment and I'll try to explain my side. You might also disagree with my analysis of the changes; that's cool, too.
You can find the patch notes I'm quoting from here. Because there are so many patch notes, I'm only going to be able to talk a little bit about each change. I'll explain it a bit and then talk about whether I approve or disapprove of the change -- although it's not like my approval really changes anything.
Bloodlust, Heroism, Time Warp and Ancient Hysteria can no longer be cast while in arenas. This is a big change for hunters, mages, and especially shaman. Bloodlust effects are a huge reason to use a certain class in certain arena compositions. 5v5 suffers the most when a teammate doesn't have a Bloodlust effect, as you give five people Bloodlust instead of just three or two (that is, Bloodlust has a much greater effect when it affects more people).
I approve of this change, but not for a reason that you might suspect. People overlook class synergies pretty often when it comes to PvP. For example, hunters work better with classes that have a strong slowing or snaring debuff (warriors and death knights are optimal choices, as they can also peel an enemy off the hunter).
Shaman, mages, and hunters have anti-synergy (or dyssynergy) because they all bring a Bloodlust to the table -- they're losing "class itemization" in this regard. Removing the ability allows each of them to become slightly worse for a time, which means they will be slightly buffed later (or in some cases not at all because of the change). It puts the classes on a more level playing ground when they are playing with each other. Long story short, it gives them more options for teammates, which is always awesome in my book.
Oh yeah, and it's nice that 5v5s won't be so bursty. I'd love to go back to a Season 2 type feel for 5v5.
The draenei racial trait Gift of the Naaru now heals 20% of the target's health over 15 seconds, rather than a scaling value. This change makes Gift of the Naaru heal for much, much more than what it's currently healing for. A fantastic change, although I would prefer it to heal instantly (no HoT) for 15% of the target's health; that's probably too big a departure from the original design of the spell.
The dwarven racial trait Stoneform now reduces all damage taken by 10%, rather than increasing armor by 10%. It also increases the dwarf's size when used. I definitely approve of this change. Dwarves are one of my favorite races, and this actually gives me an incentive to play one. 10% damage reduction is pretty huge and very needed to keep up with the other races.
The gnomish racial trait Escape Artist now has a 1.5-minute cooldown, down from 1.75. In addition, it is now possible to use and waste this ability when not snared or rooted. This is consistent with other dispels. While this is a definite improvement, I think Escape Artist would be more balanced around 60 or 75 seconds, as opposed to 90. The ability is far less powerful than many abilities currently on a 1-minute cooldown (Dark Simulacrum, hint hint).
The human racial trait Every Man for Himself has been reverted back to a 2-minute cooldown, down from 3 minutes. Incredible disapproval of this change. Humans will once again be the go-to class for alliance PvPers. My warlock is already human in anticipation of this change. (I called up Blizzard and got a free race change because I faction changed to worgen a only a few days before this change was originally announced.)
So yes, while a change benefits me, I still heavily disapprove of it. Other than Will of the Forsaken in The Burning Crusade, there has never been a more powerful PvP racial than a 2-minute Every Man For Himself.
The worgen racial trait Darkflight now has a 2-minute cooldown, down from 3, and is no longer on the global cooldown. In addition, the movement speed bonus now stacks with existing bonuses, but cannot be activated while Sprint or Dash is active (and they cannot be activated while Darkflight is active). The 2-minute change was needed; three minutes felt way too long. Global cooldown change is also huge. It was frustrating to activate the ability and not be able to slow my opponent right afterwards (sometimes in that global cooldown my opponent would be able to just jump right back on me).
I disagree with the movement speed bonus stacks, however. This seems like it's opening a can of worms for bad things to happen. I expect to see this change reverted sometime in the future.