What do you get when you take an awesome game for a classic system, revamp it with new features and multiplayer, then make it portable? Awesome-ness. In the form of Super Mario 64 DS. It has the new mini-game feature, which you unlock more features for by playing the game and catching rabbits, and the multiplayer mode. In multiplayer, you can play in a full 3D level with your friends, trying to catch stars, via DS Wireless communications.
How does the single player mode stack up? Very well. They took the old Super Mario 64 for N64, took out all the blury graphics and gave them sharper ones, and gave it 3 new playable characters: Yoshi, Luigi, Wario, and Mario, of course, but he's not new :P But the sound has also been improved.
Forever Fall Monkey: Go to Tall, Tall Mountain on the third floor of the castle. Walk up to the point to where there is a waterfall, and a monkey. Pick up the monkey (You can play as whichever character you want) and get to the point on the very edge of the waterfall (Don't fall in). Drop the monkey down that part of the waterfall, and it should come back up the and drop again, without you pushing it. It may take a few tries to get this right, but eventually the results are pretty cool.