As an ex-psp user myself I share similar interests in the exploitation of the dingoo. Indeed some ps1 games in fact work, some don't. Myself I have my own copies of ff7 and twisted metal at playable speeds. But fair warning - the emulator is nowhere near perfect. Specifically there's no sound as sound severly slows down games and purely does not work. You'll have to search around compatibility lists on google to find what settings work for most games and choose the right settings for each game every time (as settings do not save each time you exit). You'll need a psx bios file, but not all games will work while using it. There is an option to choose with or without using the bios. This is very important, when you recieve your dingoo, you will have to hack it (Dingux) first and load a menu local pack(containing better working emulators as well as the ps1 emulator) onto a mini sd card (or micro sd into a mini sd adapter) before you can play ps1.

On the whole, I wouldn't specifically buy the dingoo solely for ps1 emulation. It does nes, gb, gbc, and gba pretty well but snes and genesis is a bit crap. But all the emulators that are on the psp are on the dingoo near flawlessly (after hacking). There is very little interest into programming dingoo emulators so don't expect anything new to surface anytime soon. Hope this helps.