Whether you use  use cases or user stories is not as important as understanding why use cases or user stories work well (when they do).

There are many similarities between use cases and user stories such as:

• both start with the user in mind,
• neither one should be user interface centric,
• both are scenario based,
• nether one should represent design,
• both are used to represent a given aspect of a user's need (aka business requirement),
• they better be identified at the beginning of the process (whether traditional or agile),
• etc.

Just today I was reviewing a solution document for a brand new system (which replaces a legacy one) and I found lots of "pork".  Please excuse my newly acquired political vocabulary.  I found lots of features in the proposed solution/design which I could not tie back to any given requirement.  So my first instinct was not to ask "what is the requirement" but I found myself asking "Why do we need this? Tell me the scenario/story/case where this feature does something of value for the user?".

The answer could have been given in many forms but the essence of what I was looking for was a use case or a user story.

Interestingly enough, I've seen organizations adopt the concept of "Use Case Briefs" which is a way to create use cases which are very shot and are represented in a very simple table.  The size is small enough so that you can easily fit 3-4 use cases briefs in on page (81/2 x 11).

- Adrian