Pros
Hard to think of words to put here. Some of the data collection is pretty interesting, comScore is a leader in the space. The town center is reston is a really nice place to work, tons of good restaurants and parking. If you want to work somewhere and simply go home at the end of the day without caring about making a difference and becoming friends with your teammates, and keeping to yourself, this can be a good place for you.
Cons
Super high turnover, no clear path to advancement in the client service role. You go from Analyst to Senior Analyst and then most people leave the company (sometimes earlier). The next logical role would be Sales Director but all of those people are hired externally. Not much sense of community at all. Ex- people don't say hello when they see each other in the hallways (its not particularly huge office). Sketchy practices with the data. I have both experienced and heard many horror stories that are pretty poor ethics. For example, many companies take our reported data as an industry standard and report it to many other people. Often this data is knowingly falsified simply because someone "feels like it" or it will "tell a better story" when our data sets are inaccurate. Any mistakes in the data require fabrication and misleading in order to tell a story to the client and attempt to save face when the truth behind the story is usually a mistake or bad set of data, although that will never be admitted. If you want to feel good about what you do and perform honest work this is not the place for you.