Not bad to start with. Some fun jumps in there. A couple of the textures are a little confusing. On some walls with seamless textures, you can shoot one part, but not another. Like when you first spawn, the back and right walls are the same texture, but you can only shoot the back. Also on the vertical jump before the multi-platform pogo. You can shoot the wall and then you can't. Minor issues, but they could be frustrating when first encountered.
I think the staircases are a little bright, and the crystal-shaped backward/forward teleporters are a little strange at first, but that's probably not a big deal. Overall pretty cool.