Monotonous is the word that comes to mind. There isn't anything very unique about the game, and it doesn't do what it does very well at all. The quest for a high score isn't worth it here.
You're struck with no penalty for just avoiding enemies and letting them reach the bottom, there aren't very many enemies on the screen at a time, and the power-ups occur randomly without any rhyme or reason for their activation.
On top of that the control scheme is bothersome. Having to press the shift key is unintuitive to begin with, and having to hit it every time you want to shoot- instead of constantly firing by holding the key down- is an unwelcome strain on the wrist.
And the sound is bland- as are the enemies, the ship, the backgrounds, and everything else. The game doesn't do anything different or interesting and it isn't fun enough to work for a higher score. I quit partway through the second level and have no intention of looking back.