I got stuck for a while in that part where you have to crouch but there's no crouch button, don't know if that's intended or not. Managed to get past it by the wall climbing glitch.
I liked the parts where you have to focus on both screens because there's risk in both dimensions.
On the last level, just before the flag, my blue guy fell next to a wall and dropped off the map, and landed right next to the red guy, which was a cool unexpected moment :D