I like vocal harmony for the same reason I love a good brass choir or a string quartet, it pleases the senses with a richness and depth that one voice, however powerful, has a hard time matching. The best thing about harmony is how diverse it is. It works in every genre and on many levels, polished and unsophisticated. To echo one sentiment cited above, singing with a group - when everything comes together "right & tight" - and the audience is into it as well, the hair on the back of the neck does stand up, unless,of course, you happen to be a cadaver.