I really love the presentation. The sprites look good, it is atmospheric and it is all just nice to look at while playing. Definitely the strongest point of the game. Also the level design felt quite good, with the central hub and paths branching out of it. At first I was annoyed that there seems to be very limited number of save points, but in the end the items save after death, so dying started to sometimes feel like a shortcut to the middle.
There are a couple of issues though, for example I wasn't really sure what the powerups/items did. It felt like most of them spawned new enemies, and didn't give me much? It may really just be me not understanding what is happening, but it felt quite confusing. Also the game sometimes felt very punishing with spikes killing you in one hit, as well as enemies dealing a lot of damage. And when speaking about enemies, I didn't find a good way to deal with them, so they would always slow down the gameplay for me, especially the mushrooms, which I would need to shoot twice for them to die. It felt weird and broke the pacing a bit.
Overall it feels like a good entry, that could very easily turn into a great game! It could just use a bit of balancing and UX additions.