The core mechanic feels good and jumping and shooting stuff is fun, looping through the level is a nice concept but what grinds my gears is the pixel perfect jump, too hard to jump it and yet not particularly difficult, just an arbitrary reset if you are trying to do it fast.
Adherence to the theme, only one key so it fits and the game is built around it so thats great.
Original, wouldnt say is particularly original concept but not a cliche either.