I wanna be the Crystal
The last stage is alright. It has some creative sections, but also has some poorly designed ones to balance things out, including some hidden saves. Near the end it becomes more needle-ish, with some generic jumps, but nothing terrible.
The bosses are also bad. Most follow the concept of getting harder as the fight goes on, which makes bosses with higher amounts of HP particularly tedious. The last boss follows a different structure, being more learn-y and a bit more decent, although the first phase is mostly standing still and once you kill the boss, the game freezes for a couple seconds to show some dialog windows that must be closed manually, which might lead to uncomfortable situations like the game un-freezing when you least expect while your hand that controls the arrow keys is pressing the Enter button, and then one of the projectiles killing you before your hand is back to its normal position. Specific, but happens more often than it should (It shouldn't happen at all).
When you end up hoping for a mediocre section in a fangame, it's just intuitive how terrible said game is, and that's exactly what happens here. Highly not recommended.