FSVO "usable" depending on what game and how popular it is. (Disclaimer: This information is ~ 1.5 years old. YMMV)
The big problem with PCSX2 is that it was written with only two threads, and then cpu growth went horizontal (more cores) instead of keeping vertical (faster cores), so if it's not a popular game that gets its own tweaks (Final Fantasy anything, Persona, etc) you can be using a major beefy box that could run Skyrim on "ultra" while running a Xubuntu VM, and you're still going to have a bad time trying to play the original Ratchet and Clank.
Of course, rewriting the thing would be a massive undertaking, so I kind of gave up on watching it. Sad, really, considering the awesome library of PS2 games out there.