I really enjoyed playing this one! I've noticed that one thing people usually get wrong is fluid movement, I think you got a very good movement here, nice job. Also nice poweups, the slash feels great.
Now there's somethings didn't like: I didn't quite like the camera position, since it always leaves the side I'm heading super hidden, and the side I'm not, shows a lot. Maybe the smooth camera needs an offset to the direction you're looking.
Combat is a little rough, since I can't properly aim/hit at the pace I'm trying to and the damage of enemies is pretty high, and also I lose all coins I gathered when I die. So, pretty rough.
And finally, double jump is so frustrating, specially when level design forces you to use it pixel perfectly, but sometimes you just won't double jump, it just doesn't work sometimes, even when pressing space, and you fall all the way down, super frustrating and annoying.
Let aside those perks, I think this is a really well made game!