Oh, and knowing you, Action9000, what do you think of the music, especially the opening song?
One of the best opening tracks I've heard in a long time. B)
One thing I do appreciate about SSB:Brawl is that it's very artistic in general. It's almost "high-tone" when it comes to its content outside of the immediate fighting-game gameplay, with the beautiful visuals and remarkable soundtrack. I really see this as an artistic game and am *generally* very pleased with what they did with it.
I downloaded the full OST from smashboards as Petrie mentioned (it's 1GB and 313 tracks in total). While there are some tracks that disppointed me a lot, others were unexpected and truly well-done. Here are a few that stood out for me:
A remix of Mario Raceway from Super Mario Kart (SNES). This remix is fantastic and very elegant, with touches of both acoustic and synth elements.
A remix of Luigi raceway from Mario Kart 64. Another very well-done remix which I approve of.

Rainbow Road from MK: Double Dash. I never played this game to know whether this is a remix or not...I don't think this is a remix but I could be mistaken. It's a nice track though.
A wicked remix of the Castle theme from Super Mario World. B)
Remix of Bramble Blast (Donkey Kong Country 2): Okay, this is one I was very disappointed with. This track has been taken away from it's "beautiful" roots and thrown into a more upbeat style. I'm also not a fan of the instrument choices; they just seemed very unsuitable in general, even for the style that the track was remixed in
A few songs from Sonic Adventure, including "Open Your Heart" (Sonic's main theme), which I approve of.
A lot of the OST takes originals from other games and throws them directly into the game, as opposed to remixing them first.