Guests highlight the exceptional quality of the guides on the "Best of London with Westminster Abbey and National Gallery" experience, noting their extensive knowledge and engaging storytelling that enhance the tours. Many reviews commend the seamless organization and the ability to skip long lines, making the experience enjoyable and efficient, especially in crowded conditions. While most feedback is overwhelmingly positive, a few customers express frustration over cancellations and refund issues, suggesting a need for improved communication from the tour company. Overall, the majority of participants recommend the experience for its informative and memorable nature.