As for the simplifications: Roads (and rails and ports) connect everything. Meaning everything has to be build adjecent to a road. Furthermore I heard that the amount of buildings is small (plopables should make up for this, and I think they are nice) and that diversity if limited.
The other simplification is that the entirity of God mode (shape your own terrain) was removed.
As for the social network integration, I'm afraid it might up like the Sims, where you're poked to post on facebook for the littlest of things you do. (Haven't played for years, so I dunno if you can turn that feature off.) Besides, developper videos focus a lot on the highscore boards.
Oh, for the always Online DRM, I heard it's really always online, so losing connection midgame would result in getting kicked out of the game. No confirmation on this one though. Also, the game is Origin only, a system known for it's security, tolerance and ethical bussiness doing.
On the topic of maps, In sim city 4 the towns bordered, allowing you to make nice regio scale cities, here that is no longer the case. There are going to be ugly highways connecting everything.
Oh, and some more.
-No modding: No support and no permission. It would interfere with the MMO part of the game. This combined with EA and you know there's going to be overpriced DLC.
-All savegames are stored on the cloud. Luckily we all know EA is to be trusted and won't just pull the plug out of the game servers once it's no longer profitable.
I'll just link you guys to the EA forums thread.
Link. It's not that this is a bad game, I'm just quite afraid that it won't be great.