Great, thanks!
So, every lvl had a clear problem which can be expressed in a game-mechanic language, that is great. Difficulty jumps all around - weird.(Two of the later ones were easy) So I figured the best lvls are those, where you can use broad concepts to solve it and worst - through fiddly timing. Two I solved by accident, but maybe I didn't grasp the concept that turned them from fiddly into conceptual.