The game is overall amazing.
The controls are incredibly tight. The movement mechanic has a fresh feel to it, and is at its best in this game. I am not much of a pixel fan, but I loved how well the artstyle fits in. The sound effects are spot on and, combined with the screen shaking on every move, make for a very impactful and satisfactory gameplay, every step of the way.
No difficulty is particularly challenging, but some levels cause you to think and carefully plan your way forward. I also liked how you did not need any tutorials to make the player comprehend the way new enemies and other objects function. For example, explaining moving crates in level 22 was effective, since that level was rather laid back, with the focus on the new mechanic.
Finally, I really wanted something more from the ending, but I must admit that the "You did it!" sign at the end of every level filled me with a sense of rewarded effort I had not felt since Mario's "Here we go!" ;)
I can only imagine how hard or time consuming this project was. But you have a great formula at hand, so just keep on giving!