Great book! This is a valuable "deep dive" into a useful technique for measuring perceived usability. The System Usability Scale (SUS) is one of a number of industry standard usability questionnaires (SUMI, QUIS, USE, etc.). After building user experience groups in several companies and consulting with dozens of corporations on software product usability, I've settled on the SUS a cornerstone to user experience metrics programs. I prefer the brevity and simplicity of the tool and scoring to other similar surveys and have benefitted from having SUS benchmarks for comparative analysis. Jeff Sauro is a thought-leader in usability and a leading authority on quantifying the user experience. His website (measuringusability.com) is a wonderful resource for UX professionals and Product Developers. His writing style is engaging and he has a knack for presenting complex social science research and issues in a clear and useful manner. Jeff has continued to push the evolution of the SUS in UX practice and has developed an "all positive" version of the SUS that on first blush seems more user-friendly than the original. Highly recommended as a follow-up read to his book "A Practical Guide to Measuring Usability."