I have a few, I wear them while gardening, because as they don't have arms they don't ride up. This means that your lower back stays warm. As someone else mentioned, this means that they are excellent when working with horses, when your arms seem to spend an awful lot of time up above your head.
I did buy a very glam fake fur one a few years ago, but sadly it didn't make me look glam, I looked more like an extra from The Flintstones. I passed it on to DD - and was rather taken aback to see her wearing it in a photo on facebook, pinned lopsidedly, to a fancy dress party, as a cavewoman! 