Okay, I've beaten 15 levels by now, and I think this is enough for me now xD
Level 14 was absolute hell, I think it nearly took me two hours to beat that one alone.
The wall jumps felt like they wouldn't always work consistently (sometimes, the character is jumping more to the side, sometimes higher, right into some spikes or sometimes the character wouldn't jump at all) which was very frustrating.
The many levels had many little cool ideas! I especially liked the one, where you had to use the loop mechanic, to build up momentum.
Overall very fun, if you can bring up the patience.