Mario Kart: DS is not only the best game in the series, but also highly portable while still remaining great fun.
Gameplay: As with all mario karts, the majority of the gameplay lies in racing. With 8 different series cups, you have plenty of chances to try your hand against the other classic mario characters.
The battle mode has returned in glory as well, and finally Nintendo has given AI control for battle mode, which is, surprisingly, quite good.
Speaking of AI, the AI in Mario Kart does not let up. Finally, it seems, we have a game that remains challenging throughout the game, whilst still remaining fun.
The second screen on the DS is what really sets this Mario Kart apart from the others. An easily readable map lets you see exactly where you are in the lineup, and also shows approaching dangers. In fact, it is entirely possible to run a full race just looking at the bottom screen's maps, I have done it, and it is quite a different experience. Of course, this is not what you really want to do, it is merely a wonderful reference tool that will have you wondering how you ever survived without it.
I did not have access to online multiplayer, and so that will not be discussed.
Graphics: Graphically Mario Kart DS is amazing. Often times I had trouble believing I was playing the game on a DS, it just looks that good. A few problems with environments being low in quality at very few points in the game, however, bring the score down into the 9 range.
Sound: The sound is standard mario fare, complete with the same voices Mario + Friends have been using forever. The music follows suit. It is really nothing terribly orginal, but certainly not bad.
Value: The massive array of modes and races presented in Mario Kart: DS is amazing. This game will keep you entertained far beyond the time that other games will become boring. I highly recommend it.
Tilt: At last, the definitive game for the DS has arrived, if you own a DS, this is an absolute must have.