We're now just over halfway through the various Class Blogs.
Overall, I think things are on a good track. There's very little overlap between specs. On one hand, this does mean that a lot of people are losing old staple abilities they've had since vanilla, but on the other, everyone will get something that makes his or her spec feel pretty unique.
In a lot of ways, I see this as a kind of reflection of what happened between Cataclysm and Mists of Pandaria. Cataclysm had a pretty impressive talent overhaul, but it was Mists that really totally tossed out the old system in favor of a new one. In a similar way, Warlords involved a grand "ability purge," but Legion looks like it's going full-throttle and really knocking specs down and building them back up.
So far I haven't seen anything that's enraged me. I was mostly happy with how the Warlords ability purge turned out, though I think Arms Warriors wound up getting far too much cut out of them.
But I think that the problem with Arms was that they created a mechanical identity rather than a flavor one. Arms became the spec of "big hits," which translated to fewer abilities.
Their approach this time around is, I think, much better. They're trying to home in on what makes the specs appealing and really focus on that. Sometimes there's a clear difference of opinion of course - while I'm really happy to imagine my Shadow Priest essentially being an Lovecraftian cultist (or at least using those powers,) I know a lot of people associated them more with a kind of gothic reflection of standard Holy priests. While Blizzard argues that Demonology was always supposed to be about summoning demons, I don't think that transforming into one was "off flavor." Seems totally reasonable to me that a Warlock who studies demons would try to become one. But it would overlap too much with Demon Hunters, so I think the new/"old" flavor behind Demonology works out just fine.
We still have four classes to go through, and Demon Hunters might have their blog post at a later date, as I'm sure they're still locking down what the core mechanics of both specs will be.
We probably won't get a full ability list until the Beta comes out (hopefully this month.) There are a few examples of things like Blood and Unholy Death Knights and Protection Paladins' AoE systems that I'm really unsure about, but for all I know they have other AoE tools that we're just not seeing yet.
With all the new talents getting designed, there's going to be a ton to look over. For now, I like the attitude behind their changes.