You work together with the individuals you UE with to get to and into buildings, but once in, the experience for most people is quite personal, photographing and absorbing your surroundings. Taking in the history of the place your exploring too. Being in a group adds to safety, and sometimes you might miss things if you were on your own.
It does bring together people of very different backgrounds, which I quite like in a way. Though there is an element of socializing, for instance we usually go for something to eat or drink after a good explore, its not the same as going out on the piss. The conversation does generally revolve around the explore, but after a while you do get to really know some people, long term UE'rs are passionate and fairly intelligent judging from the people I've met, and I have made some really good friends UrbExin'.