DS had a bunch of great games for its time. Not sure how well they hold up anymore.
For example Zelda Phantom Hourglass and Spirit Tracks were already weak entries on release relying heavily on the touch screen control gimmicks which were new at the time.
Kirby's Canvas Curse is probably my favorite 'touch' game and perhaps the best touch controlled game on the system.
GTA Chinatown Wars has been ported to a number of better systems. Metroid Prime Hunters was an impressive tech demo but a very repetitive game.
Square Enix released a bunch of great remakes and remasters like Chrono Trigger but since then a number of those titles have been remade again for other systems.
The Castlevania games are certainly worth it, Fire Emblem, Pokemon etc. but Nintendo was at this weird time in their history when they started to experiment with stuff like Nintendogs and New Super Mario Bros. while the GameCube was burning in the background.
It has a very dissapointing to 'sequel' to Yoshi's Island called Yoshi's Island DS, a Golden Sun sequel that basically ended the franchise and the surprisingly good Metroid Prime Pinball. Two 2D Sonic's that were pretty awesome and a very dissapointing Sonic RPG by BioWare. It revisited both PlayStation 1 era 3D gaming and the very best of the SNES. Contra 4, a sequel to Okami, the best Tony Hawk game since Tony Hawk 2(?) and the worst Kingdom Hearts game all on the same system.
A rabbit hole that has no end or bounds, literally because the licensed Alice in Wonderland game is a hidden gem. Yes, you could even hit the lottery with licensed games.