Nice short platformer. Plays nicely, I'd say. Attacking animation isn't the prettiest but it's very clear and it works. :)

Maybe it's just me, but I feel like the princess's sprite is too big...? Thus movement feels slow and jumps aren't... satisfying? 

The ground is a bit smooth, considering how pixel-y the characters and rocks are. But then again that smoothness is good for slopes and round edges (and the player slides smoothly by the way, which is good), so it's up to you. Character sprites are good as it is, and the difficulty is good for introductory level. 

Edit: Oh, almost forgot. The in-game "Help" is a bit outdated?

Overall, good job!