Pros
Exposure to a broad set of technologies. Tight collaboration with innovative academics. Cambridge is a great place to work, if you can get there. Not-for-profit status alleviates much of the financial pressure you might feel at a for profit (esp public) entity.
Cons
Commute can be brutal. New senior management is steering the ship in new directions - which can greatly upset the 75% of the staff who have devoted their careers to the more traditional Draper work. (Not saying the new directions aren't the right thing to do, just saying that a lot of good people feel seriously disenfranchised.). Not a lot of turnover at the mid-management levels, so it can take a long time to rise through the organization. Not a lot of corporate growth over the last two decades - so there aren't many new management opportunities created.