I have been playing it this weekend. It's pretty fun for a free 2 play game though it's not something I plan on dumping money into. It's sort of like TF2 with more mayhem going on. The gun customization is pretty cool so far. I haven't unlocked a lot of options for it yet but still built some cool shite.
I posted a site in Gardokis thread the other day about it but they are out of keys. This site has plenty of keys left though Keys Website Trailer Video about the game