so after 172 deaths i can say this game is a blast to play. simple but perfect. the only things i would change is.
1 a marker showing where checkpoints are.(because i would like to know that when i die i wont be back at the start of the level) ,
2 the penalty of death (that being about 1 second) be reused as in some levels you have to jump where spikes that don't kill you are. and there no distinction of which is which, and i think it slightly unfair to make so you have to die to find the correct path and then penalise them for doing so .
3 the camera, the camera should move so that the player can see more space ahead of him than behind him. the camera system currently could be alter pretty easily to fix this. instead of the player being outside an invisible box you parent an object to the player with an offset based on the direction hes facing something like (camOffset.localPosition = (spriterenderer.flipX ? -1, 1)* offsetAmount ). and then just re-target the camera controller to that. if you keep the offset amount smaller than the distance from the player to the wall of the invisible box there should be no jerky movements and it would be a lot nicer in my humble opinion.