How did this exercise help you build empathy with prospective users?
The interview does not sound like a survey at all, rather it feels more like personal documentary or story spoken out by the person been interviewed. This allows the reader to put himself/herself in the position of the person been interviewed. Therefore I was able to fully understand and related to some of the frustration of the person been surveyed. For exmaple I was able to understand how the fact that he dislikes going to many standard “recommended” tourist locations during his visits to a foreign city.

This method of interview also allows me to dig out some of the needs, and frustrations of the person been interviwed

How did the clustering of information help you to understand user needs?
Clustering information allows me to categorise some of my user’s common needs and frustration. Thus I can pick and prioritise what problems I need to focus on solving for my client in my product. Eliminating some of the niche and narrow needs of a particular user or group.

What was difficult or challenging with the technique? How would you do it better next time?

The most difficult part of this technique is the way that we had to put frustrations and needs of our users in different categories.  Sometimes the categorization of user needs can be confusing because there are times that a certain need can be categorised under two or serval groups.