Should I buy a Nintendo DS Lite or a Sony PSP (for an adult)?

This is for an adult (early 30's). I really enjoy puzzles, brain teasers and that sort of thing. I probably wouldn't buy any other types of games. I have a 360 for that. I want this for traveling, camping ect..... and yes I have an iPod, so really don't care about the picture and movie capability of the PSP. Any thoughts and advice would be much appreciated.