PSP isnt just a handheld gaming console, so how you can compare it to DS is amazing lol, even when you just compare the gaming side of it PSP wins 90% (excellent graphics for such a small thing, etc... etc...). But from what i can see PSP dont have any true pick-up and play games, unlike the DS. For example you can whereever you are pick up your DS, chuck in WarioWare and play a few minigames. Where PSP is more intense gaming. Its all down to opinion tbh.
But im going to buy a PSP.