Ouch.. got me at the ending there. :)
Probably slightly repetitive in the middle, just a series of jump and nothing else. One more mechanic might have spiced up the interest during the middle (of an admittedly short game). But the art and music work very well together.
It's also nice to see the little things like the trail when the character jumps, and the actual animation when you turn etc., rather than just single frames in each direction -- if that makes sense.
Very impressive for only 11 hours, imagine if you had the whole week! :P