Nice first try!
I've been reading some of the other reviews, but none offered any really substantial, constructive criticism. I hope you read this review and make use of my suggestions, because you don't have a terrible game here! I beat all 30 levels, and noticed a couple things.
First of all, your character doesn't face the way he's moving. The easy way to fix this problem is to add "character._xscale = 100" to your right movement code and "character._xscale = -100" to your left movement code. (I know that one sounds a bit knit-picky, but it always helps!)
Secondly, your game doesn't do anything to make it seem fresh throughout the experience. You do the exact same thing and it doesn't really challenge you. The moving coins in the second half are kind of cool, because they challenge the player to beat the level as fast as they can. What many games do is add new twists throughout the game to constantly change the way you think about the game.
Some music would help, too! Ask a musician in the audio portal to use their music if you don't want to make your own, because that stuff's always great!
Some extra polish would help make the game even better, too. "Modern"-looking menus and interface, graphics and even some of the hit test and controls. For example, your guy "bounces" on the bottom of the screen if you touch the bottom. Try and make the hit test a bit smoother, or remove the bottom altogether and have your character reset whenever you fall past the bottom. Fluid transitions between levels would help, too. The game is keyboard-controlled, so using uniquely keyboard controls makes it a lot better.
By now I have probably bored you to tears or forced you to ignore the review altogether, and I hope you can forgive me for that :P Good luck and I hope you'll let me know when you put out a newer, improved version of the game! :)