Super Smash Bros. Brawl is ALMOST a single reason to buy a Wii. Almost.
The main thing I worry about in this game is the fact that they tried expanding the roster toward the end of development. I personally think they should not have done this, including characters like Sonic the Hedgehog and Solid Snake, which really had no business in the game and are not even Nintendo franchises. Not to mention while palette swap characters from melee are not actually copied characters anymore, a lot of them have too similar movesets where a common person might call them a copy anyway.
Another main issue is that this is by far, one of the most broken games in fighting for head to head combat, where one character has its own tier in the competitive community and in many cases, even if you are a noob, there are several broken characters that can overcome all others with simple spamming and it's really annoying, and some game movesets seem to have been made without half the stages in the game in mind where many of them suicide you off the screen or down a pit.
But the game is tons of fun, as usual you have your items and the new addition of the Smash Ball, which activates your characters SUPER ABILITY, which all characters have one, you have to break the smash ball to get it, and each hit it goes flying around the stage, you need to get your characters to hit it enough first or do a single strong blow to grab it. Some of the super moves are more useless than others and some are down right cheap.
There are many different modes in the game, like tourney, Brawl, and a customized brawl option allowing for large character, or everyone to go super slow or super fast or what not. And a single-player adventure, the star attraction of the game,
Nintendo gave a somewhat story mode, although it's hard to call it that, where you play through multiple characters through multiple cutscenes, and even fight bosses. In some cases you can choose who you ant to go in from a limited selection, but once you complete a stage, almost all allow you to choose all of the characters you have unlocked for that stage, so after beating story mode you may be interested to go through again, although the replay value for story mode.
Main issues with story mode is the fact that characters are terrible to react to your commands, Pressing jump or doing smashes or attacks, sometimes takes to long to actually happen, you will notice this mostly in story mode, and always online, but not as often with brawl mode.
Another main issue is platforming, which is in some stages in brawl and all over story mode, which is awkward and slow and unrealistic, it's like your are driving a flying tank and trying to control it in the air, and the fact that with a lot of characters, especially in story mode, jumping is pretty much giving an open opprotunity to murder you.
One main issue most people have with the game in General, whether Brawl mode, tourney, story or whatever, is how many simple hits have the ability to fling you half way across the screen. In Story mode, flying off the screen to fast can kill you off the screen, and even at around 0%, many have the ability to super man you around the darn screen. In Story mode for example, the bad hit detection ghost shadow samurai things with the twin blade can literally knock you around the screen 5-10 times before you kill them and sometimes there are bugs where they keep going until around 200%, or if you are in an enclosed room, you can't get blown off the stage, so they keep doing it again and again and again.
New characters and bosses are in this game, and strangely enough, regular single-player mode from Melee and Smash Bros is also on this disc, as well as creating your own stages, which is a mixed bag, and tons of music, original and arranged, and being able to choose which song plays most often or not at all in each stage.
There is also an online mode, while it is fun, and has a spectator setting and a challenge a random person around the world type of mode, as well as a friend codes list to fight people you know, it suffers from slowdown and bad hit boxes, and some characters lose a lot of potential online and some gain very bad advantages unless of course, items are on, but even then...
Super Smash Bros. Brawl has tons of content, and it will keep you busy, but it focuses to MUCH on content, and it seems to have hurt the game, but the series still is enjoyable and I am looking forward to what they do with the next game if they do decide to make a sequel.