Pros
If market research is your thing, Nielsen is the place to be. The company is involved in many different research markets from TV and media, to consumer packaged goods, to internet trends, etc. Depending entirely on who you report to, Nielsen can be a very friendly place to work for and can allow a great deal of flexibility in vacation, work-from-home, and other work-life balance areas. These kinds of issues are defined by each individual manager rather than company policy, so it makes a big difference who your supervisor is.
Cons
Since the company was purchased by private equity, senior management seems to be focused solely on cutting costs, and not on producing quality or building the business. Most departments are now highly outsourced, and more cuts are made every day. Morale is in the pits and nobody has much confidence in their future at the company. In addition, communication from senior management comes at a trickle when it comes at all, so rumors take the place of real information and make employees even more uneasy about their jobs. Even with the cuts, more and more work is being taken on with ever shorter deadlines imposed on workers by management.