Honestly pretty underrated in my eyes, has better flow in level design than the original Rush to me but haven't played that one in a while. Plant Kingdom, Machine Labyrinth and Ghost Ship are all classics, and the other levels are just decent instead of painful which is a liberty not every Sonic game can claim to have.

Don't really mind the sailing sections, though that might be my sailing game bias talking. They're pretty straightforward and easy minigames, and you can replay levels without having to do them again so I don't find them an issue like most do.

Also that music is pretty great even by Sonic standards.