Backer beta on Monday, but apparently it's only 4-5 hours worth of gameplay. The guys at Obsidian streamed some of the game at Gamescon today/yesterday:
http://www.twitch.tv/twitch/b/557987029
Starts ~1:37:00 in.
Game looks... ok. I was really looking forward to this one, but I'm not sure it looks any better than Divinity: Original Sin. Maybe it'll look better in person. The UI looks kinda cheap and dated too, so I hope they make that a little prettier for launch.