Too Repetitive
This is fun for about ten minutes, and then you start to think, "is there any point to this?" Each level is the same, basically, with the same enemies, except with a different scrolling background and boss at the end. The bosses take waaay too many hits to die, and have really predictable firing patterns.
This is what Konami's "Raiden" would be if instead of being the most fun arcade upscrolling shooter ever, it had been forced to simplify itself into level after level of the same thing over and over.
It's a nice concept, but it needs work to improve playability.