This seems like more of an Alpha. I frequently can't connect, where a small white window sits for a long time. Even go to a large white screen and have the same issue. I've only dabbled with it a few times and It is hang city.
Then I connect, and the keyboard on my VM on the host is way screwed up, yet not on the Host. I connect with another remote control app, and no problem at all.
Just started trying the Mac Beta. Haver Host and Server set up on Windoze 2012 R2, which was totally easy. The Mac Viewer has frequent disconnects. The other issue is after a restart of the Windoze box, the Mac viewer will connect, but the window stays blank and won't connect. It seems not until I log in on the Windoze box will it work.