I'm sorry, but Level 20 is just... bad. In all the other levels, if you fuck up, oh it's just a small room, no problem. But in this level, if you fuck up, you have to keep playing the same long level over and over again... miss a jump? Gotta redo that segment. If you aren't sure how to complete a segment and you try to experiment, you force yourself to redo the lower segments over and over due to your inevitable descent. The rest of the game is good and granted, Level 20s bits are cool, but being forced to play them over and over again due to minor mistakes is frustratingly hard and not worth doing.