I do like the game, however at one point I lost interest -- specifically after losing 5 times in a row after the first checkpoint. Being used to casual easy to pickup games, feels like the difficulty curve is a but too high too fast.
That said, if you make the players more engaged before upping the difficulty, the game will improve as a whole.
So maybe make a few more platforms in the beginning that have blocks preventing you from slipping? Enabling the players to get a feel of the physics before making them fall to their flamy death.
While this has been done before, the level design in the later levels literally bends your mind. This game is best judged on latter levels -- and it's totally awesome. Don't tempt yourself into using the walkthrough.