Good. I like how the game is about moving around and learning patterns, as opposed to forcing the player to fit through impossibly small gaps that are barely larger than the cursor. Some might complain about the graphics, which are worthy on the Atarii 2600, but I think they're all they need to be. Good use of color. Is it just me or does the game title on the splash screen change colors after a certain amount of restarts? The music is... a bit annoying, but it's mostly due to voices used. The composition actually fits the action.
The game was nowhere near as frustrating as it could have been. I had little trouble playing over again until I got that last medal. I love what happens when you pass the 2-minute mark.
If I can offer anything, it's the the game is nearly the same every time (other than the placement of of the gaps in the tunnel/wall obstacles), so the player can actually memorize the game. I understand you want to make it progressively harder, but maybe the obstacles could be randomized within a specific "tier" of difficulty?
Ultimately, it's still possible to screw something like this up, butyou did a fine job.