Love the concept but the controls don't feel very smooth. Needs more coyote time and the ability to swap midair. I like that the music starts out slow, but I rarely get past the opening trill so after several attempts at jumping over the buff gunslinger dude it starts to become jarring. The run should always start slow and have no gunners for a while.
A sound or animation when swapping is a must for future updates!
As others have said, the obstacles should stand out more in their environment.
Excited to see where this game will go next- maybe there could be a second action for each character and more types of obstacle that are introduced as you run, or more combos which require both characters to complete (such as jumping up and then attacking in midair to clear an enemy with a shield). Good luck!