Some of these updates look like they are going after cosmos:
1. Action bars, if the screen shot they provided is indeed how their update will change how action bars are going to work, then I don't need that feature in Cosmos.
2. Quest tracker, I use cosmos feature to help me keep focus on quests I am working on. ie...I check off all the quests that need to be done in the hinterlands (some of the quests originate in Tanaris and are listed under tanaris, so they are easily forgotten.) Blizzards answer looks as though you can highlight quests and they will be put on your screen for a visual reference. To me, this is a better solution.
The above two points are almost enough to get me to drop cosmos. I use two other feature of cosmos all the time: I'm a stats monkey and cosmos battle stats are pretty good. And Cosmos rogue helper is great as it offers an easy to see visual indicator of how many combat points you have on a monster and how much energy you have.
If I can find something that offers these two features I'll be dropping cosmos the day this blizz patch comes out.
3. Rolling on Bind on Pickup (BoP) item confirmation, thats a no-brainer that is in cosmos. Everybody using cosmos should have that option on. And hopefully there is no way to turn off this feature when blizz releases it.
Chat bubbles:
Eye candy. I may use it once in awhile but, I think I will find it annoying me to see bubble popping up on the screen all the time. If they offer a toggle to shut it off, I think I may do that.
Meeting stones:
Why they were not included in the original release is beyond me. This works the same as the find game feature in WCIII. Press the button and in a few minutes you have a party.
The class improvements look decent. I have no complaints about them. Druid cat form should have a higher dps, warriors rage should be increasing while in battle regardless of parries, misses or dodges, priest power word shield was limited only to party members and couldn't be cast on non-partied raid members which means parties without a priest didn't get benefit of this, and the mage new spell seems to be a logical addition that will help keep them alive an extra 10 seconds. These all seem to be good improvements in areas where each of those classes were lacking but are part of those classes.
The underdevelopment highend stuff looks great and fun. I would like to see them deploy some mid and lower level content and battle grounds as well. That will be a wait and see. The discussions they have had about battlegrounds certainly leave lots of room for them to add such features.
The battleground seige looks like it will be an awesome addition. My understanding is you will get to drive and control seige weapons as part of the encounter. Go Go gadget steam tank w00t.