Pretty good
I love games like this, so it's always good to see a new one come along. There's nothing too unique about this one, but it's a fun, solid production.
Music was really good, I don't think it changed with the gameplay but it seemed to fit surprisingly well with the action at times.
The enemies were all fairly standard but there was a good mix of them and the AI worked well. I only got halfway so maybe I missed out on the really interesting ones.
Graphically it's simple but a few of the touches like the rotating background gave it an impressive look overall.
Only thing I didn't like was being shoved back to stage 1 when I died. I like games that I can keep working at until I complete them.
You could definitely make a great sequel from this, hope to see more from you. Nice work.