I too just purchased a DS yesterday after much consideration and I must say it's been a long time since I was this excited about a console! There's just so many games on it that I want to play.
The main reason I purchased it was to play Mario Kart but I knew there were several other great games on the machine, I just wasn't aware of how many. I purchased the Mario Kart pak along with Sonic Rush, then went out and bought Advance Wars: Dual Strike and Castlevania: Dawn Of Sorrow today. I've also just ordered Trauma Center and Animal Crossing just now too.
I think this is probably the best time to buy the DS - there are many great games available, many more just on the verge of coming out or already out on import, and it has so much support (especially in Japan, where I just read that 8 of the top 10 games in the all-format charts are DS titles), that it is sure to have a long future ahead of it.