I liked the part where I was fighting the game's cover image.
The boss turning into a bullet hell was a bad choice, considering the movement wasn't fit for that kind of gameplay; it's hard dodging bullets by jumping if I can barely control where I'm going to jump. I also had no idea when I actually hit the cover image, because there was no indicator whatsoever, nor a health bar.
Platforming was okay, except the double and triple jump felt more like "air breaks" than actual double and triple jumps.
The rewind mechanic is also massively underused for the game; it's essentially only mandatory once (at the very beginning when introducing it), and even then it's just the caveman. I only found out the third stage was a cyborg because I specifically went out of my way to see what would happen if evolve too far (spoilers: it's nothing!), other than it wasn't used at all. But I do think the mechanic itself it interesting.
But at least the graphics look nice!