I like that a level editor is built in - I messed with it a little and created a
very simple level. Seems like the people who do level editing might want the ability to make multiple levels though?
Gameplay-wise, I'd often fall off one unit blocks. I eventually figured out I had to jump first and then move, but I'm used to jumping and then moving, if that makes sense (here that results in falling off the platform)
Also, checkpoints would be nice, it's frustrating to have to start all over after making it to the second or third layer of platforms. Alternatively, you may want to consider starting with shorter levels and gradually increasing their length/difficulty.
Anyway, looks like a neat project overall. Good luck with future development