As others have said, the movement takes a bit to get used to, but I like the concept of having to constantly switch between three control schemes/abilities. I'm not great with these types of games though, so I ended up mostly just moving with the triangle's recoil when there were a lot of enemies. Checkpoints would be nice as well.
I enjoyed the sound effects, but I didn't even notice the music until I went back to check if there was any because it was so quiet. A slider or volume toggle would be nice for that. Also, the firing sound effects got very repetitive (what with me using the recoil to move around...). I think a bit of pitch variance would go a long way.