First, let me say that I absolutely LOVE Savannah, GA. So that may have a lot to do with my glowing review of this tour company. After all, a tour company is only as good as the city it is guiding you through. That being said, I did several tours with several companies while in Savannah and this company was definitely my favorite. The number of tours coupled with the price was the first thing that attracted me to this particular tour group. Most companies have only one or two tours. Savannah Walks has 6 and if you schedule 3 then you get a special rate that is cheaper on a per tour basis than most other tours in town.
I went on the Savannah Stroll (a general tour about Savannah), the Civil War Tour and the Ghost Tour. I had the same tour guide for the Stroll and the Civil War Tour. He was a very good story teller and even brought a banjo and sang southern songs while we were walking. The ghost tour was interesting, but the guide was not as good of a storyteller. I went on a ghost tour with another company that was better, but that company only offered the ghost tour. So I still consider Savannah walks to be the better company all around.
I advise spreading the tours out over 2 or 3 days since it is a lot of walking. But, you do not need to be in great shape or anything. However, if you have any kind of medical condition where you cannot walk or stand for an hour or more at a time then I advise taking the riding tours with other companies (they offer carriage or bus tours at higher prices).
I have visited Savannah twice and gone on walking tours with Savannah walks both times. Listening to the history (I am a history buff), character, and mystery of the city has made me fall in love with it. I hope it does the same for you. If you ever consider visiting Savannah, please feel free to ask me for pointers.