Oh yes. A fantastic game. You start out with eight characters, and each has two karts. As you progress there are four other characters to unlock, each with two karts of their own. But somewhere between the start and unlocking the last character, each character gets a third kart. Eventually, you'll have twelve characters and thirty-six karts, allowing 432 different combinations. There are sixteen new courses for Mario Kart DS, and four from each previous Mario Kart. The retro tracks are nicely done--the SNES and GBA ones look good in 3-D, The MK64 ones are faithful to their original incarnations, and the MK:DD ones don't have everything they did on the GameCube, but are great all the same. For example, a shortcut in Yoshi Circuit is missing. The sound is really good and not overdone (except for Daisy's voice which I witnessed killed an old lady). The graphics are what we wish MK64 had. The characters and karts are all in 3-D. The items are all sprites (except the blue shell, the Bloope5r and maybe another I forgot), but they're not badly done. Oh, and you can jump again!
And multiplayer is really fun and easy. If you know someone with a DS, you can play with them, nothing else needed. There's also Wi-fi for playing online (most TMKers do, but I can't because I can't connect right). I play against people I know at school sometimes and it's really fun.