PSP has a lack of games, is too brittle feeling, has really bad software, is not fun, and for the most part, games take forever to load since there are loading times off the disc (which can fly out).
With the DS or a GBA, you can play instantly on the moment like waiting for something, on transit, on lunch, etc. By the time you've loaded something on the PSP, you could have played many rounds of games and enjoyed yourself with the DS.
The PSP is just like a shruken down PS2 with all the negatives and baggage with it. It's not even good for movies since you have to buy large memory sticks and deal with crappy firmware unless you spend money on overpriced PSP UMD movies.
Supposedly, Bob Ross is coming out for DS and Wii
Yes, THAT Bob Ross. Paint a happy little tree.