Pros
In just my first week, I worked with more clients in more industries than in the prior 10 years. I had incredible experiences in my nine years at B+B, working on global and high-impact projects with some very impressive, talented people (clients and co-workers). I had the chance to begin new initiatives and see them through to completion. My co-workers were my family and I developed incredible life-long relationships. I learned countless new skills and was continually challenged.
Cons
Oh ... working in a highly creative environment means lots of changing direction, a good deal of uncertainty, clashing of personalities ... resistance to using some digital project management tools. Stress and working long hours are part of the package. I saw many talented people move on to bigger and better things (which can be a pro, really ... just means a fair amount of turnover).