Super Smash Bros. Brawl is one of the best games ever made. If you don't buy this, you're missing out on a lot.
The gameplay is basically the same, but now you have different items to affect gameplay and Final Smashes, which can be used by breaking a Smash Ball and using the Special Attack button (Often B). The controls are also the same, easy to learn controls, though there are different controllers with the conversion to Wii.
The music is good, though most of it is just music from Nintendo (as well as Metal Gear Solid and Sonic) games, in the forms of remixes as well as some music taken completely from its game.
The graphics are a lot cleaner, and the Final Smashes look wonderful.
Multiplayer is always fun, and if you have friends, this game won't get old. Even without friends, if you have Wi-Fi, you can spend your time playing against people around the world, testing your skill against some of the best (or the worst).
There are 22 characters you start with: Mario, Peach, Bowser, Donkey Kong, Diddy Kong, Link, Zelda (who can transform into Sheik), Samus (Who now has the ability to become Zero-Suit Samus), Yoshi, Kirby, Fox, Pikachu, Pokemon Trainer (With Squirtle, Charizard, and Ivysaur), Kirby, Meta Knight, King Dedede, Ice Climbers, Lucas, Ike, Pit, Wario, and Olimar.
One notable feature is the Subspace Emissary, a new story mode made for the game. It starts with Mario and Kirby fighting in a Stadium, but a mysterious force plans to take over the world (kinda). It's surprising how well they show the story without the people talking.
The Wire Frames of Melee have also been replaced by Alloys. There is also a game to acquire trophies rather than to just insert coins and hope for the best.
There are a lot more good things about this game, but I can't list them all here. Well the reason I didn't give it a 10 is because the Subspace Emissary gets repetitive quickly and some characters are too overpowered. Still, Brawl is a great game and I really recommend you buy it.