I have used the harmony feature several times in different ways. While it is not state-of-the-art by any means it can be useful. I've even used it to harmonize certain realtracks.
I originally tested it for use with generating harmonies for a vocal track using a midi melody as a reference. This track is the result. It was finished in Power Tracks using chorus and delay to mask the generated artifacts:

https://soundcloud.com/cxp-2/johnny-angel