My overall impression about the game is that, while there's nothing really wrong with it, it's just not that fun to play. The biggest factor that makes puzzle platformers fun (at least for me) is the puzzle element to them, and in this game there wasn't much puzzling to be solved. The second biggest factor that can make a platformer stand out to me is if it's a metroidvania style game with a big world to open up and explore. This game wasn't either of those so it wasn't really up my alley, but I can still appreciate a good platformer that's just a test of platforming skill without being a puzzler or a metroidvania. In this game the only challenge was pulling off jumps where you need to change blocks once or twice in mid-air, and it felt like there were only a few points that were even close to challenging. The slow pace of the game took away from the allure of a skill-based challenge -- I agree with the other reviewers that the guy ought to move faster or have a "run" button if this is meant to be more of a skill game than a puzzler.
So if I were to try to make general suggestions for your next games: 1) spend some time coming up with clever puzzling level designs if you'd like to make a puzzle platformer, 2) build a huge interconnected world for the player to open up and explore if you'd like to make a metroidvania experience, 3) make the game pace faster and have some more intense challenges if you'd like to go for a skill game. Or all of the above if you think you can swing it.