The game definitely has too many random elements for the level of strategy it asks of you. Even making each battle less random as to whether or not you will take damage would help a great deal.
The jump detection is not working correctly at all, I'm lucky if it registers a jump 10% of the time. This isn't the case in the original XNA Starter Kit.
To those of you who keep saying the controls are what make it hard, you're right. If the controls were actually tight and responsive like one would expect, the level design wouldn't be difficult at all. One is struggling more with the controls than enjoyable level design, here- though there is some of that too.
 "Trigger Knight"){kind=icon}
 "Straw Hat Samurai"){kind=icon}
 "XNA Starter Kit:Platformer - AS3"){kind=icon}
 "Nano War"){kind=icon}
 "Meat Boy"){kind=icon}