Graphics leave much to be desired, but that's probably the least of your issues (no one who reads "made using flash" will expect HQ animation, anyway). Controls are pretty responsive considering they're mouse guided, which is nice. Each stage adds a little more difficulty and a different background: No new ships, no boss battle at each stage end. It's too repetitive, and the game is not really addictiong so you could ignore that flaw. Only reason to play the game more than once is NG medal system.
Your only boss battle is little more than a regular enemy with more HP. It can be easily kited going left to right. And after dying it just dissapears like any regular enemy, too.