It's a pretty good idea, I used a similar one before, but I think you should work more on the balancing: movement speed, gravity force, jump height, bullet speed, etc. At the moment, I get the feeling that I need to stop the bullets at the exact right height, which is finnicky and somewhat random (you yourself said it's "trial and error", which doesn't sound like a fun game concept to me), which is why I'd leave more leeway by increasing jump height and slowing down bullet speed. The high gravity makes it very punishing, which I guess could be a good thing if you're making a rage game, but this feels more like a puzzle platformer to me, so I think it would benefit from more accessible (i.e. easy) skill-based elements and harder/more complex puzzle elements (horizontal bullets, enemies flying back and forth, freezing crates in mid-air?)