Sakurai is releasing a lot of information lately. Good luck with the 60-some updates he has left to go without completely giving away everything.
EDIT: Though, if the strategy guide is coming out that early, I guess it doesn't matter.
I remember people saying the same thing about Twilight Princess, and look how that turned out. Some songs were recorded, but a vast majority were MIDIs. It wasn't bad at all, though. Brawl's music should be good, even if it's not orchestrated.
So basically, he'll be a Marth clone with different animations. Eh, his attacks are different enough. Looks good.
Hopefully heavy characters don't all jump 30 feet into the air like Ike here.