How detailed does a user persona need to be?

When it comes to user personas, employ the “keep it simple” method. One page is more than adequate.
There’s a diminishing return as the amount of information goes up, especially in the areas of personality traits, interests, likes or dislikes. It’s impossible to generalize a large population of users with that much detail.
Here are the three most useful pieces of information:
  1. The ultimate goal of the job role. In other words, if they were as successful as they could possibly be, what is the benefit to their organization?
  2. Criteria for measuring success. Make sure it can be quantified.
  3. Obstacles. What are the biggest obstacles preventing them from becoming as successful as they can possible be?