I like that I can join my son's PE worlds while he plays on his iPod. I always hated the touch controls. Now I can play with him using an xbox controller.
The controls and UI are a little too mobile centric for me though. Hopefully they continue to fine tune the Windows 10 version a bit more. When originally announced I was hoping for essentially the Xbox One version of Minecraft for PC rather than the PE version.
Just came out of beta, if anyone's interested. Price will be bumped up in 29(?) days, and the 'free to owners of Java edition' offer will end with that I believe.