Pros
I worked for a brief time for F2 as an intelligence advisor in early 2015 and still have yet to work with another team as passionately committed to excellence as F2. From the first moments of walking in the door till I walked out every moment of each day was dedicated to raising there client services and engagements to a level of thoroughness, accuracy, and depth I didn't think possible. I found their approach to be both innovative and challenging. The employees I interacted with described the work environment similarly and when projects were underway it tended to have a very fast pace in order to provide the highest quality products. That pace and quality was also well appreciated and rewarded.
Cons
My time with F2 wasn't long enough to learn of any cons. They have continued to reach out from time to time for advice/guidance in new and innovative methods as they continue to strive for excellence.