You're too hard on yourself.
It's a pretty barebones concept, sure, but it's got some nice gameplay.
I really like the idea of using score to shoot, except that without any warning it can mess you up pretty bad in the early game if you don't realize it.
I don't think the "Buddy" feature did anything at all. I only tried a couple of the weapons but Buddy didn't seem to do anything special.
I think you could make some of the early enemies slowly ramp up in difficulty, too. They're so easy for roughly 6 or so waves, then they get a lot harder right after the boss. It's kind of like practicing against a target range before going up against an elite squadron or something.
Anyway good game, but please look into those things I mentioned.