I'm not sure about the PSP, but half the people with a DS are just playing Nintendogs in my experience, which is a big shame. Its a stupid fad just like the tamogotchi a few years back.

Its silly really - there are some great games out there for the DS and people are missing out on them by just buying the one that gets the most hype.

Handhelds are something you either like, or don't, in my opinion. I like handhelds for when I'm travelling - but I would never call them a substitute for a real games machine.