I've just finished it! WOOO!
I'm not a big fan of RPGs but I have to say that this is brilliant. I remember watching my brother play it for endless hours when I was much younger, but I didn't understand his enthusiasm. Then when I saw the trailer for Fallout 3 last year, I got really excited and felt that investigation of the originals was in order.
One of the greatest games of all time? Absolutely. It's firmly punched itself a place in my top five favorite games list!