Nintendo did really good with this release, but it has some flaws
First off, we'll start on the story(Sub Space Emissary). You start off as either Mario or Kirby, and they seem to be in a tournament of some sort. After Mario and Kirby are finished fighting, you can see meta-knights ship in the background, following it a radish-black cloud. You fight off the enemies and then fight off against Petty Pirana, who is holding peach and Zelda captive. You save them, but without warning, you can see 2 R.O.B's opening a strange machine. The machine goes off and the stadium is engulf by a huge dark sphere.
As for the gameplay in SSE, it reminds me of Kirby Super Star, which was and still is an awesome game. You basically go from point A to point B, beating up baddies, opening doors and whatnot. There is also an "RPG" element in SSE in which characters equip stickers to enhance their attack, defense, charged attacks, etc. I, for one, felt that this was un-needed and out of place, especially in a fighting-side scrolling game. I also feel that the developers dragged out the story way too much. Sure, i like my games to be more than 1 hours long, but after awhile, You'll start getting a "Will this ever end?" feeling in your stomach.
Next is the Multi-player aspect of the game. This is where brawl shines the most. You can either play with your family/friends offline, or you could battle people all over the world online(about time, amirite?). You can edit your item selection, damage ratio, stock, time and things of the like. I prefer online more due to the fact that i can play with friends who don't live very close to me. But with every good thing that comes, there are problems that come along with it. Lag is a very big issue online and i hope that Nintendo will fix it soon.
Extras
Now when you are playing a game like brawl, wouldn't you want to show off your achievements to friends? This is where the Challenges section comes in. It displays your current achievements and achievement in which you have not completed yet. The achievement could range from beating classic mode on easy to beating boss battle mode on intense difficulty. There are also trophies that you can either unlock via challenges, or completing the game with characters in either classic or all-star mode. You can also pick up trophies in SSE or the coin launcher mini-game, and you can get stickers in SSE, the coin launcher mini game, or doing regular brawl.
There isnt really much to talk about afterwords, besides the music, which i think that Nintendo did a really good job at. Oh, did i mention that you can get CD"s too?
If your already a fan of the SSB series, you will definitely enjoy this latest installment in the series. This is one of those games that anyone can play, whether it be a video game veteran or a first-time player.