My thoughts on the Xbox so far.
Way too long to get into a game from the first cold boot, it was probably an hour before I was playing something.
The UI/OS is fast and responsive, everything is almost instantaneous. But we already knew that, my only issue has been a little bit of slow down when I was viewing my notifications while playing Ryse.
The voice commands and Kinect both seem forced and tacked on. Some times kinect can't hear me despite an almost perfectly quiet room. Also by the time and responds you could probably have already used the controller for whatever it is. Voice commands seem like a half baked idea which might not have been ready yet, obviously it was pushed as a major plus for kinect to justify the price rise.
The controller is great, my only two issues are that the d-pad sometimes doesn't register a move and that the rumble makes a really strange noise when it vibrates. It's actually quite loud and pretty annoying.
I only have Dead Rising 3 and Ryse, can't really give an informed opinion as I've played 30 mins of each. But Ryse does look bad. Also was getting some random messages about not owning the rights to dead rising which meant I wasn't allowed to install the game. Took me probably 15 tries to get it to install without the message popping up, very strange.
So far I think it's a solid system and I'm very impressed with the hardware and OS/UI. The software on the other hand is very average, Ryse might be returned tomorrow.