SOTN is one of the only games I'd say is almost completely perfect! There a huge map to explore, tons of items, abilities, endings, satisfyingly addicting combat, and probably the best control of any 2D platformer ever made. It even has a really good story, as simple as it may be, simplicity is one of it's strong points (like we can feel Alucard's struggle through events we witness and some of his lines, instea dof him badgering on about "life sucks" and looking very brooding like other heroes). With everything it has to offer, there is only ONe major problem myself and I'm sure everyone else has with the game: The Inverted Castle.
It breaks the pacing of the game and takes it to a sloppy halt. Progressing through the inverted castle is irritating and can feel more like a chore than anything exciting. The word to describe the enemies here are CHEAP. Gremlins placed in front of entrances to rooms can mean knock back to the previous room if you're not prepared, the skeleton's projectiles bounce too far and for too long, and the beam skeletons... 1 or 2 hits can kill you, which really isn't fair! Sure, the boss fights are excellent, but you could've just placed them in the normal castle or in a newly designed map to complete after the original castle; their strength doesn't lie in the inverted castle itself.
It's sloppy, lazy, and for such a brilliant team, I can't believe they just inverted the map and made repetitive segments, overly annoying enemies, and annoying or confusing to get through areas. What should have been done is something similar to Aria; a new map with many ideas and parts of the original map but still a new map. Or if I remember correctly, Harmony of Dissonance had an entirely new castle to explore (been years since I beat that game).