For each of the 2 techniques (user observation, think-aloud):

1) What kinds of information and insights did it give you about the usability of the prototype?

User testing with the help of prototypes was very helpful, it provided me with information on whether the design was successful in reaching out to the user and it needs to be altered.  The testing began with giving the user tasks and based on  the list the user  had to perform the tasks. Certain observations were gathered while the user was performing the tasks. This was a little awkward for the user as he knew he was being monitored.

2)What aspects of the technique worked well or were frustrating?

This method may not give me the details of what exactly is going on in the users mind as the gestures may mean something else and we may assume otherwise. Also talking to the user continuously was distracting the user and putting him in an awkward situation.