Not good.
This game is not good. The graphics are okay, but the rest doesn't seem to be.
First of all, the sound does appear to be loud. You mentioned that, but that doesn't change that it still is. It's a minor thing, but can be frustrating. Variety of enemies is small, which is a small minus too, but it is. The worst thing in the game are controls. The ship can't go fluidly from going two directions at once, and then switching one direction. It just stops, so player has to let go of all the control keys for a moment to turn here he wants.
Additionaly, the idea is nothing amazing, but the game does not only have flaws. It's playable, has some kind of bosses, power ups, actual background which is cheap, but still is, and some kind of story added to it.
You can't submit score anywhere, and if you die, and wait few minutes, you will have few last bosses in front of you, floating, waiting for you to replay the game and rape you.
For me, the game has more flaws than pros, but it's your first game, so It's not too bad.