Excellent and addictive.
The best kind of flash game is one where you just keep saying, "A couple more goes, a couple more goes" . This is one of those games.
It could use some powerups, like a temporary shield. Not one that makes you bounce off obstacles, i've seen that utilised to annoying and frustrating effect, just sort of pass through them for ten seconds or so. That would be good.
Smooth visuals, but not too much so that it slows down terribly. I gave it a ten, only because there's no 9.5. That extra .5 can be achieved by adding powerups, like the shield and stuff. Other than that, it's great.