Tedious
I thought the game was creative and the levels were unique. I was somewhat stumped on the one after the cloud level so I checked out your walkthrough. The solution, I thought, was not very intuitive. One thing you will hear me say alot about games is the balance between challenging and hard. I thought this particular level required too much precision for a platformer. It assumes that the player knows things about this game that are not typical for a platformer. Thats ok, it just needs to be taught at some point. Specifically, the expectation to use the side of the game world and edging your friends to the brink of platforms, let alone the jump reversal.
You might suggest we think outside the box. Well that would be fine too except you do a good job teaching the player exactly how the game functions up until this point. To be frank, the solution didnt even occur to me as possible. I used the knowledge you provided (which all good platformers have a learning curve of some sort to allow for more complicated puzzles) but the placement of the friends would not have come to me in any reasonable amount of time given the previous levels.
If there was no walkthrough, I would have quit after 5 minutes of that level. I would be curious to know how many people used that solution without looking at the walkthrough. It could just be me. If thats the case, then it is obviously more intuitive than I thought.
Having said all that, I did love the characters, the level design, the level of creativity and the music. In fact, I liked everything but the leap in the learning curve, which can cause confusion and frustration for some players.
Thats all I have, good luck on your future projects!