Most of the JWs I knew were pretty normal. I can remember a couple of people who were sour most of the time, the kind of people who responded to "good morning" with "what's so good about it?" And there were some MS and elders who let the position get to their heads and could suck the fun out of any gathering. But I found most of them to be kind and friendly people.
Ironically, part of that perception probably comes from my frame of reference. My mother is one of the most dour and bitter people I have ever known. She rarely let her guard down. She could be perfectly nice around other JWs, though you could see where it was forced from time-to-time. But with her family, she was as negative and downtrodden a person as I can ever imagine. Compared to her, even the most contrarian JW was pretty mellow.
I think the dividing line was that some JWs were anxious for that last day to happen, while most were content to live their lives without worrying about it. To me, it seems as if the more hardcore you were, the more miserable you were. Because the greatest day of your life was so, so close but never, ever arrived.