I am a big fan of all the integration they are doing, from One Drive to Xbox One Screen mirroring I think that is going to bring a lot of value.
The first big hiccup I think MS is going to face, is the push for a MS account during setup. Most people do not have a MS account, and while it isn't required for the upgrade, MS makes you jump through a few hoops to setup without one.
I predict lots of complaining and conspiracy theory's on this fact alone. MS needs to push the 15GB of free One Drive space and all the integration points as part of the marketing push.
I do love my 365 subscription, btw. You never hear about that, but as a guy with teenage girls, and all the cloud space and my ability to manage Office across iPads and laptops, very, very nice.