I honestly think I've played harder. Well, that I Wanna Be The Flash Game comes to mind. I am quite impressed at how complicated it is. As the name suggests, it's quite unfair. It's mostly because you have to collect the coin(s) in every level. That really contributes to a lot of deaths.
The music is quite good. Okay, it is really hard. It just takes a lot time to beat each level. You have to count on so many things going right. It seems like this game fulfilled its purpose.