I think the major "plus" of Nikonians is the generally high degree of congeniality -- little if any of the "better than thou" attitude that appears on some other sites, especially attempts to belittle so-called newbies. There is a a high degree of sincere sharing that recognizes that helping someone else learn or improve does not detract from anyone else. Of course, if you have a technical quation you can call Nikon and get a good answer. But asking amnog your fellow Nikonians often elicits a discussion that goes further than just the answer. These people frequently have tangential ideas and other ways of looking at things, that are both refreshing and that offer alternatives to the "book answer."
When I get something new this is usually where I start to learn. Admittedly there are opinions as well -- but they are usually interesting and flexible. I join in saying "Thanks!"