Play until bored - it won't get any better.
Graphics aren't amazing but for that time quite good. The problem is that there's only one view - blue ocean (sometimes you'll fly over some land and sand where you can't even see a plane or a bullet flying at you) and that view doesn't change through all game. The sound as many have already mentioned is terrible. And that buggy bleeping that continues through 32 levels can drive you crazy. The controls are sluggish and you won't be able to evade you enemies if you don't think ahead which is hard to do when a bunch of enemy plains spawn out of nowhere or even worse - from your back.
The gameplay is simply monotonous and if you played one level - you could say that you played it all. The AI is.. wait, there no AI, the planes just fly randomly and that's all. And the whole time you monotonously shoot those planes by tapping the button like crazy.
There almost wasn't any fun when playing this game, after about five levels I only thought "When this torture is going to end?". Monotonous graphics, monotonous sound, monotonous gameplay and nothing classy about it.