PSP for me .... dont use it for music or films just straight forward gaming. Ds is being aimed at children and non gamers mainly hence the brain games etc
The DS is great, its small, light and the battery lasts forever. It also has some of my fav RPG's like the FF series and Zelda. I Have played on the PSP but wasn't all that impressed. Good graphics and all nut it left me with a dis-intrested feel.
I have both DS & PSP, the psp is far superior graphically but the game selection is terrible, other than grand theft auto, liberty city & vice city stories and god of war there really are not that many top titles, its a shame because the psp is a great handheld, I recently got Go! explore the sat nav for psp works a treat if it wasnt for this I might have flogged the psp. The DS is pretty weak when it comes to graphics, maybe a little better than old N64 titles but the thing is most of the games have a cartoon feel to them so graphics are not important. The Ds has the touch screen aswell which makes games like brain training etc.. possible! ok if your a harcore gamer and you dont have a ps3/ps2 get a psp but otherwise I think proper gaming is best left on consoles like PS3,PS2 & 360, If i had to pick the best handheld I would get a DS, so much more fun and literally tons of good games!
I have a PSP that we bought a few years ago and at the time loved but it went the way of most gadgety things and now lives in a draw unloved and unplayed with. It is awesome and the music videos on it play really well, the games graphics are better than the DS lite and I just prefer the shape and style of it over the DS lite. You can get a battery pack that attachs with a spare battery so it lasts longer which I don't believe you can get with the DS lite also I find it more stable and sturdy as it doesn't have the opening and closing function and is just a solid unit.