I didn't go into the booth, so I can't comment on the sound, but I was able to listen to the voice acting. Slippy's voice is NOT as annoying--it's almost a joke on his previous voice. Heh.... I'm sure the music will be very good, as David Wise is on the job.
Rare has definitely worked hard to make sure that you can't blame the system for a mistake. Fox can do all sorts of crazy--and fun tricks using his staff. Link may have to start studying under Jackie Chan to compete with Fox....
They didn't tell me, but I can guarantee it: Rare ported the code from N64. The first thing Rare needs to do is to take a hint from Silicon Knights and rewrite the code for the GameCube. Then they shouldn't have much problem fixing the other things wrong with this game. Good luck, Rare--it needs a lot of work, but I know you guys can pull it off. Don't be afraid to delay the game! Everyone here would rather see it fully optimized, and hopefully Nintendo will agree.