I love it too
Jumping/platforming games are the ones I like the best. And this is a fine example of the genre. I have stopped on level #15 of chapter #2 (I haven't skipped any levels!). I am going to favorite this game to come back to and finish later.
What did you do right?
-Infinite lives, and no annoying noise or animation for dying
-Several different ways of jumping, but not too many
-Little sprites, so that you can see a lot of the level at once
-The traditional for a platform game: obstacles, timing, etc.
The parts I liked less were the ones that involved the arrow up/down squares too much, especially when you're moving up and can't quite see where you are going to land until you get there.