I think what's throwing people off is your attack and jump buttons feel exactly backwards. Or in other words A should be jump and S should be attack.
It's like on NES games how the vast majority of games had A (the button on the right) for jump and B (the button on the left) for attack but every so often a game did the opposite and when that happened it just felt weird.
Well since a keyboard control with arrows to move on the right but your action buttons on the left, you need to flip them from what they would be on the NES so instead of leftmost button attack rightmost jump, you'd need leftmost button jump rightmost attack.
This is really the only thing I can make sense of as far as the overwhelming amount of reviews complaining about the controls, because they weren't that bad (I mean some games really do have bad controls), but they did feel backwards is all.
Pretty good game for having made in such a short time and I don't think any of the low scores are justified. I'm giving 4 of 5 stars because there is a fair amount of lag in this, though honestly I'm not sure how it could be avoided given the nature of the game.
Also I think it's level 7 or one of them where after you grow the vine the camera fails to pan back to your character, so you're just walking blind for a bit unless you finished with the vine near your player.