Well yeah, lot's of games "work" but they're not playable (unless you're into S&M and like to suffer
).
I've tried dozens of games and I can't think of even one which is playable i.e. not excruciatingly slow (well maybe Resident Evil when you're alone on screen).
Note that I'm talking about all the typical PSX games here(i.e. 3D): I've heard that some 2D games are quite fast, but if I wanted to play 2D games then I'd boot up Picodrive or some other older console emu and enjoy decent speed, not use a PSX emulator.