The DS ain't got the graphics, but the touch screen really is fun on some games. Just bought the KH reminiscent "The World Ends with You". Incredible battle system. You actually control two battles at once, one with the stylus (with a slew of different stroke commands) and the other with button controls.
The PSP is the clear winner in graphics and most game choices, just like the PS3 or 360 over the Wii, but it's the originality of each system that makes it new and interesting.
I'll just play my 360 if I want pure graphic excellence, or my PS2 if I want PSP graphics and awesome game choice. :\