Really good! A very solid Pico platformer. Enjoyed my playthrough quite a bit.
My one gripe is that a few jumps feel just ever-so-slightly on the technical side. Double-jumping straight up to a high ledge always took several attempts, in particular. Not sure if any of the blame lands on my computer's performance, but it felt to me like if these could be made just a touch gentler, that would make the game flow better.
Ended up finishing in just over 22 minutes with 55 deaths. Could have been lower, but I didn't realize there was a limit on deaths (something that should be explained or removed!) or a penalty at the end so I didn't play it as safe as I could.