[JeanPierre]

Well, there are some comments just about that in the "coming soon" part, and it seems that the selling point is about making multiplayer easier for you compared to Minecraft.

Whereas you have to host a Minecraft server yourself (or host a world on a LAN) in order to play multiplayer, Skycraft doesn't require you to do that. All you have to do is share a link with your friends. In addition, you can "[i]nvite anyone to fly or walk around in your world in spectator-mode", which I optimistically intepret as "walk around in my world without buying the game". (Of course, that's my take on it.)