pretty good
im working on a platformer myself so i understand alot of the code that goes into making this, i was actually just working on my game minutes b4 playing yours which is cool. anyway, my only complaint is the lack of exit, which you know about and you could have done it, you just ended the game early, and second the moving physics, they work fine, but i find that landing on the boxes up top was kinda annoying because of the slippery effect the physics give, in my personal opinion get rid of, or lessen that slide effect, or just adjust how much/ fast you move. overall though it was a good platformer for a first game and all that good stuff.
oh ya, and if you feel like responding to this review, what coding do you use to make the level follow you up and down, i have left and right with the level moving instead of my character, and my character uses a physics engine to jump, but i cant find a code/ make one for the level to have an up and down if you know what i mean, im limited to what i can put on what you see on the screen.