Ventajas
Although this is a massive company, they are very intentional in creating engagement among the teams, specially cross-departmental teams within the same region or country. Also, higher management is very transparent with the whole workforce regarding profits, goals, shortcomings and next steps. Even though I work in a fairly small account with very low headacount, and don't really talk to other teams (because we work remotely), I still feel I know what the company is up to and what to expect. Finally, my favorite part of my particular position are my two direct managers. I feel very greateful for and inspired by them.
Desventajas
It is a big company, so it's hard to know what kind of environment or manager you will have before you actually get in. For instance, a couple of my close friends started working in the company within the same year, but we all work for different accounts. We agree that this is a great place to work overall, but the specifics of workload, relationship with managers, communication, time off requests, etc. vary significantly, so you might hear very different descriptions of what working for RWS is depending on who you ask.