Pros
The office culture is great. You are pretty much guaranteed to make friends there if you are a social person. This is the best part of working at Arup. The relationships you gain here, both professional and personal, are very valuable. They are very talented people working at this company, globally. Internships are paid very well, and usually turn into full-time positions. Learning and growing is encouraged. The benefits are generous and the career development is clearly defined. Paid overtime until you reach a certain grade is nice bonus.
Cons
You will work hard, and you will mostly not be thanked. While my personal boss was a lovely person, the final say is in the hands of more senior staff. There are some really awful people in high positions who are ungrateful, unprofessional, and unapproachable—the type who people unanimously hate working for or with. The pay is not competitive with others in the industry. Arup takes advantage of the decision between working for a big name or working for higher pay. Many young staff choose Arup because of opportunity, and then leave to make more money. Sometimes they return later on in their careers when they can make more. The progression is very slow and strategic, which seems to be their idea of "fair" (not an American company). Work/life balance is not great. Lots of overtime that is not worth your sanity. The engineers really slave away for many many hours. Unless you're in non-marketing central services, you are pretty much expected to work as many hours as it takes.