@E. King
1) The game can technically be played with the Classic Controller, its just not as enjoyable. So even though the functionality is there, its not listed as being supported.
2) There are 34 levels. Additionally, because the game uses earned XP to unlock later levels, you're encouraged to replay levels to improve your time, collect all of the notes, and find the "Fuji" secrets hidden in each level.
3) Online leaderboards work but use the name you pick in the game and not your VCS username. This is because the VCS leaderboard functionality wasn't available as the game was being built so the dev used his own system (similar to the implementation in Guntech 2.0).
4) I haven't got to a boss fight yet but its still early in the day!
Its a fun game with great music, level design and is unique in the VCS library. If you enjoy platform games of the roller variety, its an easy recommendation at $20. Plus, its a true VCS exclusive!