I'm going to wait until actual user reviews start circulating before upgrading to the box from the stick. Even then, I'm toying with buying/building a small PC/NAS and running Kodi/Plex off that instead.
A lot of stuff is on there now. They have made it a point to improve their library and have done so by signing deals with networks like Cartoon Network, FX, AMC and Showtime (it's offered at a lower price through Hulu).