I never did. Does it really make that much of a difference for the game?
I only played the original game (with the latest official patch) and I was extremely surprised that every review I saw said "it's so buggy OMFG it's incredibly buggy, bugs are coming out of its ears" and stuff, because I didn't see any bugs at all!?
I mean, I never tried to "push" the AI, and I'm pretty sure in an open-ended world game like this you can make them do some pretty fucking stupid shit, but for purposes of the game, I thought it was absolutely adequate. The game overall is a stunning accomplishment from a somewhat then-unknown studio, and for having been in development for like 5 years or some shit (off and on, I'm sure).
I loved the gunplay and the environments/graphics made me want to touch myself (sexually). The sound wasn't anything to write home about, but it worked well. I understand Russian so that was good too...
P.S. If you want to see a really buggy game, get Gothic 3. Now that was a buggy piece of shit, which somehow I managed to finish twice, mostly because of the amazing feeling/atmosphere the game creates, and the game world which was absolutely beautiful...
P.P.S. Oh, or Two Worlds. Now, that's just a shit through and through.