I would recommend this activity to vacationers wanting to really "see" San Diego. Our guide had only recently moved to San Diego from New Orleans, but was very, very polite, knowledgeable about how to operate the Segways and about how to get around San Diego amidst a heckuva lot of construction and inner-city traffic.
The tour itself is not "narrated" in the way I've seen others, with headsets in the helmets, but our guide -- and dang it, and apologies to him; I didn't get his name -- was a good public speaker, and so we got the gist of everything as we were going along. There were several stops along the way (a loop from near the waterfront, up through the downtown area, to Balboa Park (Zoo and museums and public gardens), around/thru the park, and back) for rest and photos and kind of orientation. He (our guide) was very patient, polite, and professional. He knows his way around very, VERY well, as we had to make several jogs around construction and congestion both going to and coming back.
He told us a little bit about the history of several points along the route, and was very conscientious about our safety and the pace of the trip, making sure no one fell behind. We have a mentally handicapped son (in his 30s) who has trouble with balance and coordination, and the guide was super nice to him and had him buzzing around like a seasoned Segway-ist in no time!
Now, you're going to see homeless. You're going to see dilapidated buildings and neighborhoods. It's a big city and you're at ground level--this is not a sanitized, don't-look-over-there kind of activity. But if you're looking for a way to get kind of a "lay of the land" in around 3 hours, check it out. Four stars for the tour, Five for the guide.