From what I have heard it's a pretty capable emulation machine.
I have 2 though I only modded one so far. I only have PS1 games on it at the moment and it works great. I haven't tried adding any other systems due to the size of my flash drive however. It's running an old version of BleemSync and I believe a memory error from GTA 1 when it Red Screened caused issues with the save states. So the save states don't save, though the in game saves still work. However at some point I'll upgrade to Project Eris and switch flash drives and my guess is this will solve the issue. Also there is already a version of Mario 64 for PS1/PSP.