By the way, can you tell me if the GOG version contains any community patches (you know, like Bloodlines or Gothic 3, for example) or should I install someting manually to get rid of compatibility issues or any other "good old" problems?
To tell you the truth I'm not sure if I ever played my GOG copy of Arcanum
because I played soooo much of it before I even had a GOG account.
But I do remember that I installed it to check if it was working fine with my old saves and every was as good as it could be.
Now I almost never install any unofficial modes or community patches, so there is another reason why I'm definitely not the right person to answer this kind of question.
I remember Arcanum having some bugs but they were more "adorable" rather than annoying.
The only (kind of) game-breaking bug I encountered was when I found this (top?) hat item. And putting it on moved your disposition towards evil -20. This wouldn't be a problem if it happened only while wearing it. It was PERMANENT! And I put it on and off couple of times and then saved just to realize that all of the sudden everybody is hating me and I'm this super villain and I was a somewhat good guy just few moments ago.
Back then I was naive enough not to have back up saves and my save was pretty much ruined. I tried some save-editor some years later but apparently the hat did so much damage that even adding +100 disposition still left my character with -20 in general. Which made it playable at least. xD