I agree that the camaraderie on this show is very appealing. (Like you, Scrufflet, I have no patience for the cutthroat shows like Survivor.) You can see how happy everyone is to be together backstage. Some of the celebrity contestants have a reborn look after a few weeks, especially the older ones who maybe thought that this kind of strenuous and skillful training would be beyond them. I remember contestants like Jane Seymour and Lisa Rinna who just glowed about their accomplishments after a few weeks. I also enjoy seeing the ingenuity of some of the pro partners, who are also going outside their comfort levels to deal with untaught dancers. Can you imagine the risks especially the women take, trusting their safety to guys who don't know how to grip for the more daring lifts? Man, Kym Johnson almost broke her neck. Even without the risk factor involved, the pros have to be really inventive in developing moves that look complex but that are doable by their partners, who may be of uncertain skill and strength. One of my favorite partnerings was Chelsie Hightower and Ty Murray, whose training couldn't have been more contrary for a dancer--rodeo bull riding! She had to figure out all sorts of ways to retrain his vocabulary of movement, and she succeeded in making him look really good. (The fact that he was completely motivated to train as hard as necessary was also very appealing.)
Then there are the various dancers with what might be considered unusual limitations for a dancer, including Marlee Matlin who is profoundly deaf, Heather Mills with her prosthetic leg, and several dancers who were considerably older than average. It's easy to forget that the latter group includes Kirstie Alley, who was sixty (or possibly a mere 59) when she competed. She gave it everything she had and then some, and it was truly inspiring.
So there are all kinds of human stories in DWTS that add to the show's appeal for me. Oh, and one other one: the music is provided by a live orchestra and vocalists, I believe. This is huge for me. I'm always happy to see artisans get a chance to display their talents, and these days it's a real treat to watch music that isn't canned and processed through a machine.