There were 2 mechanical things that frustrated me a bit.
1. There were some monsters with no real way to shoot them. (player was too high up and had to jump onto a lower platform)
2.You can't shoot a monster that is right up against you.
This combo made the second level pretty frustrating to play. Also, not sure if you're familiar with the term coyote time, but I think implementing a bit of coyote time would make the platforming feel much better!