1) Inept Middle Management - Nielsen often promotes from within which results in managers who have good product knowledge but no idea how to coach/mentor or be a leader. Having had more than 6 managers over the years I can attest that not a single one knew how to lead a team or coach a junior person to be more successful. If you come from a successful company that holds people accountable you will eventually forget all of your good habits and pick up bad ones that make you feel dumber for having worked here. Additionally, honest feedback is rare, most managers will tell you to your face that you are doing a great job and then behind closed doors build an argument to let you go. I've seen highly talented people laid off in favor of keeping less talented and hardworking people because they simply lay-low and take orders without question.
2) Next Level Hypocrisy - the company touts it's diversity and female leadership opportunities, but there are pockets of the company that are still run like a Good Ole' Boys Club where all the managers are men and the female underlings are expected to be good girls who take orders and never speak up. I've seen several, smart and talented women be pushed out because they are strong and have integrity which threatens the male ego.
3) Sinking Ship - Based on my fortune telling skills the company is in jeopardy of completely going under within the next 5 years. The "buy" side of the business has been deficient in product offerings and losing massive clients to IRI for years. The "watch" side of the business has not been adapting quickly enough and digitally oriented leaders are going to swoop in and dominate the TV side of the business.
4) Easy to get stuck - Some of the best and brightest aren't getting ahead in the company because middle management isn't recognizing them or helping them to grow. The best people are leaving the company and the losers are staying. If you are remote it's nearly impossible to get ahead - you'll be stuck.