I think some folk have too much time on their hands, win 10 works, win 10 mobile works, and even better they are integrating really well with each other, typing away and need to send a txt, leave your phone in your pocket and get the computer to do it, missed call, win 10 lets you know. yes there are third part alternatives but as an out of the box experience I'm really liking the way its going.
as for the UI, I'm quite liking the simple design, I feel less distracted and when going back to win 7 I feel like its all a little cluttered and things aren't as simple as it should be. dot get be wrong, 7 isn't bad, but personally I find 10 better.
I rarely use my tablet mode on the tablet tho, it works fine the way it is so never really had a need to use it