There's no point arguing with him, xist. Since he clearly has never played a worthwhile PSP, he's talking out of his ass. Comparing DS emulation to PSP emulation is like comparing a go-kart to a porsche. They are both capable of arriving to a destination, but the experience is not the same.
Playing Mario RPG on a quality wide screen, vs the DS where you can maybe play the simpler games, cropped, and only if you're willing to put up with graphics issues. Fully featured Sega and GBA emulation (yes, GBA emulation is superior to running it natively: the screen is larger and nicer, and having amenities like cheats, save states, and customizable controls is always a plus). Even the NES and Gameboy emulation are superior, when I got my PSP slim I just deleted all my old DS emulators and roms because there's no point. It would be like ditching a top of the line gaming PC for an old 233 mhz. The newer system can do everything the older is capable, only better.