Art looks fantastic, the game feel is really good, it controls great. I think you could improve the camera by having it follow the cursor rather than your horizontal speed, since a lot of the time I'd rather know where I'm aiming instead of running.
The boss does feel a little tedious though. The space is so large that his attacks don't really seem to matter that much and most of the time you're just trying to get the ball without feeling too threatened. It makes the guy feel more like a sponge.
But overall, I think the game looks and plays great, it's just not all that deep.