I didn't really have any doubts that after screwing around with the 360 UI for so long that MS would screw up the X1's interface. It looks very fluid and user friendly, and (to my surprise) doesn't seem to be shoving adds down your face.
While I like the idea of notifications while I'm watching background noise TV (Sportscenter, local news, any re-run of an old TV series), I hope there is an option to turn off that notification when watching specific media. I'd hate to be in the middle of some serious Drama movie and see "ChronicReamer has invited you to Halo 7!" pop up.
9:37+ - Oh lord, you can see exactly what all of your friends have been doing and how long ago they did it? That seems a little.... invasive... I guess that's just the way "social gaming" is going. Hrmm. Bummer.
10:30+ - Aside from all the snark on GAF about "TV TV TV", I'm really interested to see how many services the TV guide feature is going to work with at launch. Hopefully it's not just big companies (Comcast, Time Warner, etc..). Although, now that I think about it, that's really no different that the guide on a DVR, and I have no idea if the Xbox can interface with a DVR to watch recorded shows. Guess that's another thing I'll probably never use.