I tried git-annex a couple of times to sync my 2 OSX and linux based computers at my house and play around. It wasn't the easiest thing to get setup and working and I couldn't get one of the OSX hosts to work at all.
I'm sure this will be much easier to use for the end user like other github products and will "just work" out of the box.
As a counterpoint, I just set up git-annex and sync'd a couple of local servers plus a remote server, with no issues, by following along in the walkthrough. Granted, it's not exactly an out-of-the-box setup, like say, syncthing, but it wasn't anything overly difficult.
I'm sure this will be much easier to use for the end user like other github products and will "just work" out of the box.