Not bad, needs some more improvements!
At the first I saw the game I thought it was like more interesting. Anyway I know you have been working hard, but mistakes happens, and you must learn frome them! First the graphics are very will done, the animation is very fast. The backgrounds doesn't have any detail, as if they were drawn in a haste. The intro screen have to be more attractive with buttons, you can't let people play with a presentaion like this! Put some intro scene, an animation or text telling the story. A button for starting the game, and a button for instruction and credits. Second the gameplay, it is very boring, honestly! Add some extra features and objects, try adding levels! Those things falling from the spaceship are too fast to destroy!
And where is the sound effects or musics? your game lacks it! it is the most important element. Anyway the game as whole is good :)