Cool game. The art is really great, so is the music.
I also liked the levels both in size and complexity. They do feel different from each other, so they all have a distinct feeling. I'd probably be more likely to explore more of them if I had a map. Without I take the exit the moment I find it and don't continue through them.
I can see the camera-lean on strafing to cause a bit of nausea for me in longer play-sessions, so a toggle in the options would be appreciated for that.