First, I'll say the only good thing about this tour was Johnny Boston. He was polite, funny, and knowledgeable. The other driver we had numerous times was Coach. He was rude, abrasive, and made us feel bad.
Second, they say they come by every 20 minutes but it was closer to 30.
I have to say the Old Town Trolley Tour was much better- we used them last time we were in Boston. We'll be sticking with them from now on.