Many friendly people, you'll find cranky ones occasionally - just like anywhere else (the British community is wonderful!) It's also where I find most of my hotels and Bed & Breakfasts.
Oh - Fodors as well, though it moves VERY fast. The topics are all over the place and can be pushed to the second page in an hour.
I've checked out many others, but Trip Advisor so far as been the best. Fodors is decent, but the items are mixed (which can make it interesting, but the posts disappear from the front page too quickly. Frommers isn't too busy.