My list of bosses...
Kurt Zisa- fun, lots of strategy
Phantom- Not fun, took 20 minutes to beat just him
Ice Titan- Easy, not much variety to attacks, (here's a hint, when battling him, don't use Aero because the ice crystals he shoots will get bigger so you can't hit them back.)
Sephiroth- harder fight than KH2, but really boring in the beginning. Didn't have many moves.
Riku Second- EXTREMELY hard. Took about 25 tries first time I played the game But it was fun. I hated having to see the SAME DANG SCENE 25 times!
Ursula(giant)- Annoying, stupid. That's what I think of Ursula. Now the FIGHT was slightly fun but it did get annoying after a while because she was trying to eat you.
Dragon Maleficent- a JOKE! Just stand on her front paw and you won't get hit. But, jump a lot, you don't want to get hurt.
Chernabog- I had no idea what he was called, (I know now) but if you weren't leveled up enough (like I was) it was ANNOYING. That battle was blah, but the music was AWESOME! I have it, and one part reminds me of circus music, just for like 4 seconds.
Riku(Destiny Islands)- He was fun. I enjoy battling every Riku becaus the charactes move so swiftly and the animation was AWESOME!
Xehanort's Heartless- He was easy, once I figured out that I had to Dodge Roll when you face him second time.
Whoever else.... post and I'll say my opinion.