Good game. Well programmed and the graphic design is consistent and appealing for 8-bit.
The game itself doesn't have distinction amongst its peers. Unfortunately it's just another platformer. I would like to see the score removed from the game as it serves no real purpose (we're in a gaming society where score means very little in these types of games.) Instead, I would like to see achievements or rewards unlocked based on how many coins you can collect or perhaps how fast you can collect them and beat the level. Perhaps the reward could simply be unlocking a new level or unlocking new skateboard tricks. Maybe you can use the coins to upgrade somehow.
I could not figure out how to pass the wall in Level 5 in the very beginning so I probably missed a tip that allowed you to jump higher. Maybe you could include a list of gameplay tips accessible thru the pause menu.
You have a solid engine here and I'm interested in seeing what you do to build upon it.