I'm evidently a pretty impatient person so for me the movement speed seemed unnecessarily slow. I found moving the boxes also quite tedious as the interactions seemed buggy/inconsistent, like they'd randomly stop being dragged/pushed by me, and then sometimes the fact that you can't easily stop them was annoying, rolling green cubes into an orange gate in the last level by accident, for example. Speaking of the last level, I encountered a bug where it never gave me the option to press space to jump up the green cube - I pushed the green cube into blue cubes counter-clockwise around the map, I dunno if that caused some weirdness?
I liked the music, and the art was generally good though the way the character interacts with the barriers was very visually confusing, especially in the first area. It seems it works okay towards the top of the screen, but around halfway to the bottom the character just walks over them. Not a huge deal, but felt I'd point it out if you plan to keep going on this.
I think overall this is a really solid game and you did a great job, even if I do have my complaints. This is definitely something to be proud of! :)