I guess it also depends on what kind of games you like to play. If you like adventure/mystery games, try Trace Memory (short but fun, makes good use of the unique features of the DS), Touch Detective (also short, but unique and fun), Lost in Blue (sequel coming soon), or the upcoming Hotel Dusk. Personally, I think the DS is perfect for these types of games.
A few of the other DS games I like/have played:
-the Tony Hawk games (American Sk8land and Downhill Jam)
-NSMB
-Resident Evil DS
-Nintendogs
-Yoshi's Island DS (even if I'm the only one
)
-Sonic Rush
-Mario 64 DS
-Trauma Center
-Point Blank
-Clubhouse Games
-Kirby DS
-Puyo Pop
-Some of the Brain games (best in small doses)
The only complaint I have about the DS is that some of the games are pretty short. Still, it's one of my favorite systems and I'm looking forward to future games for it. To address the original post, I hope you don't give up on the DS. I think there there ARE good games on the system, but you may have to hunt around a little to find some of the more under-appreciated games. Let me know if you'd like some recommendations.