He is actually fairly correct. I'm not sure that one single emulator on the GP32 is "perfect". Then again, very few if any emulators on any platform, including PC, are "perfect"... that being 100% compatability with every game for the platform at 100% speed, sound and control.
As stated above, there's loads of info on the individual emulators, check the links and download sections of this and affiliated sites. For a quick list, the GP32 can emulate VERY well: PC Engine (TG-16 in US) and SMS/Game Gear. Just barely below the level of these emulators: C64, MSX 1/2, Atari ST and NES (sound issues is about it, currently being worked on). Emulators with some problems (not 100% speed and/or iffy compatability - at least some games playable): Atari 2600, SNES, Vectrex, Wonderswan, Gameboy and Gameboy Color and NeoGeo Pocket (a new one is being developed as well). In addition there is a program called ScummVM ported from PC that plays old Lucas Arts graphical adventures with great compatability, a DivX movie player and MP3 players (an Ogg player has been started). Genesis and MAME emus are in progress with no public releases.
I'm probably missing a few to boot, but this gives you an idea. All of the emulators are usuable, only the ones "with some problems" can really be picked apart... and even on these emus there are games that run well and make them worthwhile. One noteworthy item... there seems to be much more active development/improvement of emus for the GP32 than most systems. As an example, over the last few days we went from someone starting the ST emu to having one compatible with and playable with the majority of ST games.