Pros
An excellent company to cut one's teeth, if you work hard and if you prove yourself you get to take on lots of responsibility quickly. Great location. If you're lucky enough to visit the top floor it has amazing views of the Thames.
Cons
For non-sales staff, Salary is not competative and no effort is made to retain talent. When I worked there, the company provided the absolute minimim for its staff - no kitchen facilities (access to mirowave or hot water), staff had to pay to use cutlery etc The floor I worked on had a depressing work environment. No natural light, broken furniture and very old computers. This coupled with the long hours (required to meet the ever changing objectives) made working in the London office for longer than a few months painfull.