Im kind of torn with it. I like alot of the new features, but it also feels like some things got broke in the process. My biggest peeve is the atrocity that is Xbox Music. My phone is my sole device that I listen to music on, so you can imagine my frustration with the 5 steps back that it seems to have taken. Im also pissed that when I try to share a link, that it literally just shares a link and not a description as it did on 8.0. I no longer share anything to facebook because of this and it really irks me.
I do love the new start screen with 3 standard tiles wide and the transparent tiles. Sure its mostly cosmetic, but it sure spruces things up. I also enjoy the notification center more than I thought I would.