Awesome game! Great soundtrack, flipping around and hitting things is fun, it just gets a bit mindless when you're pogo'ing off of a bunch of identical enemies, but the movement is fast and fun so I don't mind that much. The difficulty feels just right on the boss fight. It's a decent difficulty spike compared to the rest, but not too bad.
I think the regular enemy combat could be really fun if you doubled down on being basically invincible during the attack, and then make the spin attack locked behind having momentum. That would give it more risk/reward and incentivize doing cool flips.