Pros
It is definitely a good place to learn the market research industry especially as your first job out of college. There are many industry leading experts that you have access to which is great for building knowledge in the company. People are great to work with for the most part but it really depends on the team you are on.
Cons
Workload is usually high with unrealistic deadlines leading to burnout. The operational teams are a mess which ends up putting stress on the Client Service team and delaying high profile projects. Path to promotion is not well defined and upper management is in no hurry to promote deserving employees. They keep you waiting a long time for a promotion (if it ever does come) and will come up with excuses rather than telling you the truth. It is a hit or miss with managers. Most are great and will work with and advocate for you. However there are some that are only looking to do what is best for themselves.