The win 10 integration dosnt work yet with xbox one, not even for preview members. The win 10 app is cool and gives you all your profile, friends list, etc. But the play to feature/game streaming feature is not running yet.
As for the win 10 switch, do it, you will love it. It installs as an update without any loss of settings or data. If your going to do a clean install which is what I did on my laptop, you must update via the update tab, then pull your new windows 10 registry key and use that for your fresh free install. what I am trying to convey is that if you just insert the new OS via disk or USB and try to reformat, the windows key for your win7 or win8 machine off the sticker will not work for a new install. The key changes when going from older OS to the new win 10. As I upgrade the OS on the computers in my company, I am making a new label for each PC that has the new key in case there is a virus or something that needs reformatting later down the road and I recommend this to everyone.
But as for the OS itself, its a great product.