Pros
Probably the best building design engineering consultancy in the business. Depending on which group you are placed in projects are a bit pot luck but chances re you will be exposed to some amazing, once-in-a-lifetime work. You will meet lots of very clever people who are very passionate about what they do and are willing to share their knowledge. Good efforts are being made to acknowledge diversity in gender, culture, ethnicity etc. but this is still not reflected at senior management level (which will probably take time).
Cons
Concern for work-life balance is expressed by management through official communication channels but reality on the ground within project teams is very different . Worryingly large numbers of people are regularly in the office very late/on weekends. The culture generally seems to be that if you do this once or twice "for the team" it tends to become the norm. Overtime pay is only granted on a project-by-project basis but extra hours SHOULD NOT be the norm if you want to retain a healthy, happy workforce. Lack of transparency in promotions process also means people feel the need to push themselves harder (and not necessarily work better) in order to feel they are in with a shot at the next salary review. As has been mentioned by others salaries are generally lower than average, especially for more junior grades. The accepted line is that the quality of experience should compensate for this but rent cannot be paid in quality of experience. In London especially I think we a close to the tipping point where we see a mass exodus of young professionals as the life in the city becomes financially unsustainable.