I played around with it for a bit last night. There's one level that can be played solely in 2 minute matches, easy difficulty, and a few playable characters including The Villager, Megaman, Mario, Link, and Pikachu. The battles have a lot of items available.
Graphically, this game looks much more lively in 3D. While the environments, effects, and such look like past Smash games, the characters have gone the cell shading route, and this works well for 3D. I got a super smash, but have NO idea how to use it. Although the CPUs have no problem. There's also Soul Edge from the Soul Calibur series in the demo.
Also, apparently the demo is wrecking 3DSs.
http://kotaku.com/super-smash-bros-is-w ... 1634549128