This is a great way to see the highlights and to get your bearings for the city. We took the entire tour (2 hours) with our guide, Jack. Jack was excellent! The tour was informative, personal, and really fun.
When we booked it was suggested that we take the whole tour and then stay on to get to places we wanted to walk around. That proved to be great advice. We did the tour and then walked all over different parts of the city using the bus to leapfrog from place to place.
I would highly recommend the tour.
FYI, we found pricing better on-line rather than in person...at least for the time we went.