I have no idea how you have not unlocked Sonic or Snake. When you play as them during the single player, you unlock them in multiplayer. Are you sure you haven't unlocked them?
Which makes me want to mention, again, how Nintendo used them. Snake was a dude hiding in a box who, once, discovered, got to rescue the princess. Who he kinda macked on. That was awesome! And Sonic? When things look their darkest he just flies in to help save the world. That is pretty bad ass, and a hell of a nice move on Nintendo's part. A non-Nintendo character saving the day? In one of their biggest games of the year? That's bold.
You're not the only one who seems underwhelmed by the single player game. I can maybe see why. It is a platformer without precision. But I still love it all to hell. Only played through it once so far. In Japanese, so I don't really know how to get 100% completion. Oh well.
But let's look at the problems you have with the game.
1) The story is short. At least it has a story this time. The previous titles did not. It takes about ten hours to beat, at least it did for me (95%) the previous games took about half an hour/45 minutes to beat. That is a hell of an increase.
2)
It just feels, plays, looks and sounds like the GameCube edition except with a bunch of new characters and an online mode. I never get that criticism. The next Ninja Gaiden is looks like the original but with new weapons and shinier graphics. Virtua Fighter added online play and a couple new characters. As did DOA. That is what sequels do. Maybe you just don't like Smash Brothers.
Brawl looks better, sounds better and (in my opinion) plays better than the GameCube version. They slowed it down (Yay!), they removed the multiple air dodging, they nerfed the throws (Boo!). It plays different from its predecessor. Snake, Sonic, Pit, Olimar, Pokemon Trainer; all these guys play totally different from any of the characters from the previous games.
Plus the event modes rock. The two player event modes rock even more! A friend and I lost a weekend to beating those on all the difficulty levels, and we just yesterday unlocked some more. So we're looking forward to loosing another weekend.
And online! And you can build your own stages! And send them to your friends! And take pictures! And send them to your friends! And save replays (why can't you rewind or fast forward them though?). You can add stickers to your character and beef up his stats. My Mario always starts with a bazooka. He is godly. As is this game.
Oh yeah! And demos for all sorts of old games. A timeline of every Nintendo game ever. A coin shooting game.
This game is packed. It is just too bad you don't like the stuff it is packed with.
