Amazing! Lots of polish across all areas. Really, everything was excellent, but I'll specifically call out the level design. Innovative and intuitive, and great base difficulty with optional challenges.
As a minor point of feedback, I wasn't able to finish the game. I got stuck in one area where there was a drop that was telegraphed by runes.. that didn't respawn... so it become memorization =( That didn't take much away from my overall enjoyment, though!