Well worth it! We did this practically upon arrival in Portugal, and what a wonderful introduction to the city. And let's face it, these tours are all about the guides. We were very fortunate to have gotten Joao Nunez. He's an anthropology student and was extremely knowledgeable about the history of Lisbon. Plus, he's a very amiable and charming young man. We really enjoyed his company during the tour, and it was a great way to start our trip.