When visiting a new city or touring around the country, taking a guided tour is possibly the best way to get to see what you had hoped to in a fairly limited timescale for most visitors. Whether you are driving or taking a walking tour, they are as much about having fun as they are about learning about the place you are visiting so it's important the the guide you hire is able to engage with you in an informative and good humoured manner. After all if we want a lecture we would probably head off to a seminar!
A great tour guide will of course will introduce himself but he'll get to know you too and also get to know what you want from the tour. Equally he'll have a perfect sense of timing..... starting and ending on time and knowing when to talk and when to listen is vital!
When I've been on a tour I've always appreciated the special tips on where to eat and shop, those off the beaten track magical places that other tourists somehow don't seem to find... it makes me feel that I've accomplished something special and I love that! If my tour guide can provide this then I know that I've hired someone who cares and knows what I want from the tour. This is what makes a great guided tour; that feeling of being submersed in the culture and very fabric of the place I'm visiting...... and a great tour guide is one who can transport me there.