Nice game, I really enjoyed it, eventhough I haven't finished it yet. I got stuck on the underwater spikes and just lost my patiance. But I think I'll play it through later. Good music as well, I take it that you were inspired by the Metroid series, or am I completly wrong then?
I have no real complaints this far, just some minor things that I personally prefer, even though I'm aware that there are people who would say the opposite. For example I think I would like a little slower platformmovement with lower acc. and dec. I also would, as someone mentioned, like more savepoints. But these are just my personal opions, and I really think the game is fine the way it is, especially since you changed the jump key. Greate game!