A solid fighter played by many, but severely hampered by incredibly stupid and annoying 'additions' that come very close to completely ruining the game. For example, your character has a chance to fall over and lay on the ground at any given time, which is absolutely inexcusable for a fighting game. Another example is how the game gives you the ability to save replays, but only if they are less than three minutes long, and no serious battle is ever that short.
However, the biggest problem with Brawl is its unbalanced nature, with the character Metaknight having the unfortunate combination of being infinitely better than the entire rest of the cast and requiring practically no skill to use. This means that a less-skilled player can easily beat a professional just by using Metaknight, and that makes tournaments and such incredibly boring and stale.
Because of these unimaginably stupid miscues by the developers, a group of players hacked brawl, removed all the stupid crap like the aforementioned trips, and balanced the characters. The new version of the game is called Brawl+, and you can play it on the Wii.
Those who don't want to play a hacked game often find themselves going back to Smash Bros. Melee, the prequel to Brawl - a fighting game that you don't randomly fall down in.
Brawl player #2: Yep. Talk about an empty victory. I feel bad for you.
Brawl player #1: Melee?
Brawl player #2: Melee.