Not bad, but could be much better. The controls are at least a little too sensitive and it takes awhile to stop moving left or right. This makes levels with small passages and areas very difficult, like the swirl levels especially Nitrox72's with the rotating part, the X-directional level, and the Lolxdwordhaha level. It's a little glitchy too, because touching certain powerups doesn't always register, the same teleport will sometimes kill you while at other times it won't (depending on which direction you were traveling when you touched it) like the one in SlantZ, and if you hit a wall right after getting a powerup the game may register a death but you might still survive. The names of the levels at the bottom are sometimes obscured by objects in the level too. It'd also be nice to display the current number of the level that the player is on. The boss is basic and doesn't get harder as you hurt it, and it has an attack that is only avoidable by being in the goal zone at the same time.
By the way, why are some of your levels included in the user levels? Isn't the point of including those to have levels other than those made by the game creator? Or was it because you didn't get enough submissions?