Quite good for a first effort, actually
I'm glad you took the time to create a finished product instead of turning out 10% of a game expecting good reviews for a "first try." It's not a fantastic game really, but it doesn't really have any serious flaws. The gameplay is straightforward and the difficulty curve not too unreasonable; the upgrades add some zest to the game. The music is, I think, generally appropriate for this style of game. The graphics strike a nice balance between simplicity and arcade-style atmosphere. In sum, it was not an unforgettable experience, but it's a good game and I enjoyed playing it. Great job! If this was your first try, I'll definitely look forward to future submissions.