I have had mine now for about 6 weeks - I only ended up buying one because I am currently working overseas and wanted something to kick about with until I got my Wii shipped over.
I am currently playing the DS more than the Wii!!! I can't quite put my finger on is ?why?
I've got 7 games including - Yoshi, Mario vs DK II (Minis), Brain Training, Trauma Center, Spiderman 3, Sonic Rush and Hotel Dusk.... I am just waiting for Animal Crossing and Mario 64 DS and r4DS (I want a decent MP3 player instead of the Nintendo one)
I really didn't think much of any of them at first - hence the reason I bought so quickly and I was fairly underwhelmed with the DS on the whole...
but it has just grown on me - I still don't think the games are fantastic although the do while away a few hours, certainly non of them are bad games!
I am now 6 weeks in and addicted -and I've seen it all after 20+ years of gaming!!! I just can't give you a succinct answer as to why I play the thing so much - could be the touchscreen not sure.
Anyone else feel the same?