I liked the humor of the game!
I only played single-player, so the multiplayer experience may be different. I found it hard to go out to explore before the next wave came to destroy the base. Maybe having some sort of teleport for single-player mode would be nice?
The upgrades I got in the game seemed lackluster, possibly because I didn't get far enough (only made it to wave 3). I really wanted to try other weapons but didn't get a chance to :)
One minor complaint is the camera. Somehow when I was moving around, the camera would rotate a bit, and I'm easily prone to motion sickness and that swaying did not help.
Overall, this game was fun, and I loved loved loved the trailer. I look forward to playing it again in the future!