Beautiful aesthetic—really loved the art style and color palette. I wasn't a big fan of some of the sounds—for instance the throwing star sounded too mechanical to me, almost like a gun shot, instead of throwing a star. Minor nitpick, though.
Bigger issue for me was the control. Like others, I thought the gravity felt too strong, dropping the player really fast. I'm also not a big fan of Oni-style controls (WASD with mouse aim in a platformer). I personally just find the combat really inaccurate and hard to manage since the angle for fire changes both from the cursor moving and from the character changing position on the screen.
I disagree with Michael Greishofer's opinion on the merchant, and found him/her to be one of my favorite parts of the game. The look of the text was jarring, but I thoroughly enjoyed the commentary, and laughed out loud at the existential crisis comment. It is a jam, and we know that everyone runs out of time to do everything they wanted (except maybe Michael, his entry was like a full-length game and über-polished[!]), so I think there's room for being a little tongue-in-cheek about it : )
I do agree about the map, though. For me part of a metroidvania is the exploration, but having the completed map ahead of time takes away that part of the game. If it was intentional, I would argue that it wasn't helping the game. If it was meant to fill in, but you didn't have the time, well at least your heart was in the right place ; )
Overall I'd be proud to make something this pretty and polished in the time given. Nice work!