we have played this as a group of 3 and must say:
Very good game! You have everything in there, what you expect from a first time coop-survival game. Diverse building, cool battle system, constant sieges in the night, good mix of strong and weak enemies and rewarding exploration + we love the graphics atm. It worked stable in a LAN setting and after setting up a port forwarding rule also quite stable over the internet with one player dropping approx. every 10-20 mins. This was a bit annoying, because the portals didn't load instantly as expected, but overall this wasn't that bad.
We are looking forward to your official steam release and were happy we could try it out beforehand!