I've had a hand on the NDS play with the cute Nintendog, but it just doesn't impress me much, and I don't like the "plastic feeling" it gave me. Since I already have DC and PS2, I can't afford one more system in this old age(27), so I gonna say no on NDS.
Now I'm very satisfied with my new PSP, playing sports games, racing, RPGs, music and MP4 movies, even reading txts on it. Sony did a fantastic job on the portable system, always, just like their Walkman.
I found GBASP,GBM and NDS are very popular in girls and young ladies here, and they even got PSP in the same time, really crazy shopping, they don't care about how many games they want on one system, just grab all the little nice looking machines in front of them!