I really like the music but it gets too repetitive if you're bad (like me) and have to reload the menu then the game many times. It would benefit a lot from having the song continue between scene transitions :)
The window breaking is a really REALLY cool effect! Sometimes it would obstruct my view of the player too much though and I'd fall because I miss timed my jump or something. Plus it might have more *umph* to the break if it is flung out further than the player :D
The score being in the middle of the screen is also a little obtrusive.
And lastly, I think for this style of game it would feel better if the jump had some inertia to it (if you stop holding A/D you don't stop immediately in the air)
Overall the visuals are really cool and its a well done game!