I works fairly well for me. I have the CD from back when Arcanum came out and have had it installed on my computer (with both Vista and now 7 - both 64-bit). I think I was able to fix most of the graphics issues with the various patches and such, but there might have still be a couple times when there were weird glitches or the game would crash randomly. Nothing that I was ever horribly bothered by though (and I have no idea if the GOG version is any more stable).

I would say definitely try it out if you already have the physical copy.