Another thing was the Smash Ball. My friends insisted on keeping Smash Balls on. Then they'd insist on playing on Final Destination, and they'd all be Star Fox characters. Yeah. FUN.
The characters themselves were fine. It's just these two flaws just ruined the entire experience for me.
Edit: Oh, one more thing. The physics seem so awkward to me personally. I played Melee so much that I got used to them. Brawl completely changed the physics so much that it's almost impossible for me to love it as much as I love Melee.