This is really pretty appealing. I think it has a nice feel to it, and I think the amount of love and attention to detail you put into it really shows. I like it quite a bit, but I do have some misgivings about the puzzle design to be honest.
In general I'd say the problem is that the puzzles tend to rely on false challenge more than exploring the ruleset in an interesting way. I think there's more than enough room in the basic premise to make enough interesting puzzles- you really don't need filler like switch maze puzzles and invisible platforms. Likewise many of the puzzles, even those that are interesting enough to stand on their own, are cluttered with random switches and red herrings. The solution to the puzzle pictured below is really very clever, and I think it would have made a great puzzle all by itself. But it's made artificially more 'difficult' by all the extra misleading switches.

Similarly the game uses 'difficult' precise timing and unforgiving situations that require frequent resets to artificially increase the difficulty and frustration level. In general I would enjoy more interesting problem solving and less obfuscation and deliberate frustration. I have nothing against difficult games, but there's a fine line between skill based gameplay and platforming that feels more based on luck or trial and error.
Also as a side note, the collision detection seems a bit twitchy around ledges, particularly in level 11. The player accelerates quickly, and the amount of ledge overhang before he falls isn't always clear.
I hope this doesn't come across as negative- my intention is to offer useful feedback, not nitpick. This really is a good game, it's very charming and definitely one of the highest quality titles I've played recently. I look forward to seeing more releases by you.