Pros
Brilliant work comes out of DP for a reason. It has many talented individuals across all disciplines. Yes, there is free lunch on Fridays. If you are a designer, strategist, experience expert or business developer you will gain butt loads of great experience because the company is so small.
Cons
I worked at DP for years and contributed in every aspect of every client business and can honestly say that the company is a cult of personality. All accomplishments, innovations and client relations are attributed to the senior-most team members. Management is not interested in developing talent, only in talent supporting the "genius" of partners. That is a shame because they do this at the expense of building a legacy group. Prior to the arrival of mid-level management there was free flowing style and less political maneuvering.