Very fun and a method of doing a platformer I've not seen before. I did have a few moments of "ah ha" of how to use momentum as the gravity shifts.
I think to really pull off the precise platformer that this seems to want to be, some more polish on the jumping mechanics (adding some coyote time especially) would be helpful. Also the camera would often not keep up with the level design and so I would find, especially near the end of level 1 where it got to be the biggest issue, that only about 20% of the screen was showing me the area I needed to see to do the rest of the level, with the rest all irrelevant space behind me. Perhaps a set of fixed cameras that go from section to section, or a camera which leads to show what is coming up better would help. As is, I had a lot of "throw yourself blindly forward and see what happens".