I've been a long time fan of the Trackmania series, since the very first game showed up at my local CompUSA, and the main reason I bought the first game was because it had a track editor. Over time the PC series has evolved and refined to its current pinnacle Trackmania Nations\United(TMN/U).
I am happy to say that the DS version is an excellent rendition. It perfectly captures the control and crazy physics of the PC edition. You are limited to only three car types: the Desert and Rally cars from TM1 and the Stadium car from Nations. Each car moves and behaves just like the PC counterparts and that means they are still easily controllable even with the all or nothing turning commands of the DS's direction pad. Polygon lines have a tendency to show up when cars are packed in close together, such as at the start of a race, but graphically the game is very close to TMN/U. It is almost a perfect version of the game.
But, the biggest aggravation I had with the earlier versions has returned. the Copper currency has returned to the track builder. You know have to earn Coppers by winning races and challenges in order to purchase parts for the track editor, as well as different car skins and even other tracks. TMN/U didn't have these restrictions, Coppers were used to purchase new tracks, skins, and even new car models online between players but that was as far as it went. The track editors were fully functional with every part available, and this didn't hinder the play value of the prebuilt tracks.
It's a small gripe, but dropping the Copper currency would have made it a perfect port to the PC version. However, it is the best and funnest racing game I have ever played. It easily blows Mario Kart DS out of the water, or off of the track, as it were.
Definitely worth a purchase, absolutely worth a rental.