It has been working lately much more than it hasn't been. On the XB1, it's still a bit of a pain to get in games with friends (issues with party chat) but once we've been in a game it hasn't been bad at all. I had one crash over the weekend and I played quite a bit.
Conner has had a bad experience, obviously, and I think he's on the 360 version. It could be that the 360 is worse than XB1 at this stage. Can't comment on that b/c I haven't played the 360 version since the middle of November.