It's impressive how big the universe is, but as isyc said, the controls really leave something to be desired. The tiniest tap on a thruster sends you into a death spiral. To get anywhere you need the spacebar held down the entire time.
It also takes FOREVER to turn around and go the other way. I'm thrusting at max and still drifting slowly backwards, backwards, backwards.... okay, finally moving forwards.... inching along... okay now I have some momentum. Maybe it's just because I had to play zoomed out really far to actually see any movement at all and I was just going way too fast.
The speed also makes it hard to navigate in a cluster of stars. At least, I can't.
One key for thrust, one key each for left/right turns, one key for reverse, and one for full-stop I think would be sufficient. I applaud you for trying to come up with a unique control scheme though.