What kinds of information and insights did it give you about the usability of the prototype?
Verbal and non-verbal expressions both give important messages in the observation. The non-verbal expression presents the user’s direct feeling, like leaning forward to the screen or frowning, is shows the users are thinking, or concerning about something. On the other side, the verbal expression tells you details about what the user is thinking and explains their non-verbal expression. Some non-verbal expression are done consciously, hence it could reflect the real and instant feeling of the user, even if he/she is not speaking out why. So by observing both verbal and non-verbal expressions, it can tell you many detail information, even the slightest flaw of the prototype.
What aspects of the technique worked well or were frustrating?
During my observation, I find out that users are not comfortable, or not used to thinking aloud. So if I find out they have some facial expression but not saying anything, I have to keep asking the user: “What are you thinking right now.” Then when I became the one who needs to give feedback, I understand why it is hard to think aloud. It is like talking to yourself, and you need to speak out your confusion or mistakes, I felt that made me look a bit silly. However, the information drawn from think aloud is actually helpful. It helps the observer to better understand which part of the prototype frustrates the user, such as a button is hard to find.