I've been playing the alpha for the past few days. So far, my impression is that at its core, the gameplay is really good and there's a lot that can be done with it. However, I'm glad this is only an alpha. It's a ton of fun starting a settlement with your friends and getting it running, setting up defenses and searching for tokens. However, there are some pretty major changes that need to be made. First, the AI needs to be drastically changed. It's ridiculously powerful - I've never seen a settlement last for more than a day or so before getting rolled by the AI. This isn't helped by the fact that at distance, other characters look like blotches. Speaking of which, while it's very pretty and has a great visual style, the fog effects and "static" effect can get in the way at times. The bloom is pretty excessive and stuff in the background goes out of focus, so it's really hard to see any detail at range, and during the daytime looking into the sun = blindness.
While I've mostly mentioned the nasty parts of the game, as I said before, there is some really solid, fun gameplay underneath the problems.
Also something to note, it may have been fixed but last I checked, friend accounts were broken so that the password was the same as the username.