It doesn't get better than this
Graphics
The Nintendo DS is only a 64-bit system (Nintendo 64 graphics basically), so obviously the graphics are not going to be on par with those of Mario Kart Double Dash, but they are none the less amazing. The graphics lie somewhere between Mario Kart 64 and Mario Kart Double Dash. They are not quite as good as MKDD, but they are much better than MK64. One thing that actually surprised me about this game, is that on the Double Dash levels included on the game, you probably won't notice much of a difference between them and their Gamecube counterparts graphically until you put the two next to each other. All maps, characters, weapons, and vehicles look fantastic and very detailed. I honestly have no complaints about the graphics, they are 64 bits of perfection.
Sound
The sound in this game is quite amazing. It takes full advantage of the DS's surround sound capabilities and it utilizes them well. All of the games sound effects sound fantastic and they will really pull you in to a game. This is the first time I've been majorly impressed with a game's sound, but Mario Kart DS's sound is phenomenal. I only have one complaint about the sound, and that is with the music tracks. Now the music is by no means bad; no song will ever annoy you or get on your nerves. Mario Kart DS, along with Mario Kart Double Dash and Mario Kart 64, has one minor problem musically that only the original game was able to master and that is the fact that none of the songs are going to be rememberable. I can still remember the opening theme song to the original Mario Kart easily, but I really have to think hard to try and remember songs from Double Dash or MK64. This game is the same way. Great music, just not rememerable like the first. The sound is still fantastic though.
Gameplay
Here is what makes or breaks a game. The sound and graphics of a game could be great but that means nothing if a game has poor gameplay. Nintendo has proved though, they know what they are doing. The gameplay here is nothing short of perfection. There have been new weapons added, as well as the readdition of a lot of weapons that have been taken out of the game over the years (such as the ghost for example). The new weapons are cool, especially the missle. The missle will turn you into a giant missel for about 5 seconds, but you are insanely fast and and a powerhouse at the same time. The new courses are great too, as well as the ones brought back from the original game. There are 16 old courses (which is insanely awesome to have), as well as 16 new tracks. This combines to a total of 32 tracks, and they are all great. The Rainbow road in this game is the best rainbow road in any Mario Kart. I'm not going to spoil anything and say why, but this rainbow road is so much better than any of the other ones it's insane. Everything you've ever loved about Mario Kart is intact in this game, as well as many new stuff. There's Grand Prix, Time Trial, Versus, Battle, and a new mode called Mission Mode. Every game mode here is a blast, and every one of them has been expanded upon. Versus mode, for example, allows you to create rules and race in teams through random courses to see what team can get the highest combined scores. Grand Prix now not only gives you trophies for winning, but it also rates your driving ability as well. Everything here is phenomenal and better than it has ever been in any Mario Kart game. The controls are very tight and responsive, and your cart doesn't feel clunky like many did in Double Dash. Everything about the gameplay is simply perfection. Nintendo hit its mark and it hit it hard. The gameplay here is better than any Mario Kart game ever made and it shows.
Value
The value here is just like the rest of the game, amazing. For only $35 you get online racing (which is very easy to navigate and fun), as well as 5 different offline modes. This game is worth every penny and will keep you playing for a very long time. I'll go as far as to say this game is worth picking up a DS just for it. There are many courses, karts, and characters for you to play to unlock, so there is plenty to keep you going.
Conclusion
All in all this is is a fantastic game. The game is one of the best racing games out tehre and definately the best Mario Kart out there. This is a must have if you have a DS and the game alone is worth getting a DS for.