I've had my Xbox one since March 2014 ... the UI has been improving month over month. Microsoft is consistently making it better with every update. I have the kinect which get the most out of the Xbox One UI. Microsoft should sell a cheap microphone that plug into the Kinect port and give you the voice command control to everyone that own an Xbox one. Microsoft has done a great job to cater to new customer that don't have Kinect and change the UI to support both users.
Windows 10 is great and I have no issue with it. It fix every concern I had with Windows 8 and is even better then windows 7. I think many of the people complaining about compatibility issues are simply using obsolete hardware and should simply revert back to the older OS.