Pros
incredibly complex work (caused by vastly inefficient and ineffective systems and management), otherwise they pay well and they have a canteen .. when these are the best parts of your job, it's time to move on!
Cons
They say the people make a company, and in this case the people are either incredibly bullish unprofessional bullies who will tantrum and shout obscenities until they get their own way, or they're so vastly unhappy about the treatment that they never stop talking about it. Meanwhile, most people are working far longer hours than they should be, especially those in London reporting to America. London office location is dreadful unless you're a senior manager commuting via Heathrow. Actual London office is bad. Culture very young & immature. Big 'lets go get drunk every night' culture. Desks packed in like sardines, temperatures through the roof (>25degrees at your desk in the middle of winter). Bathrooms disgusting. And on top of this, their systems and processes are the most inefficient I have ever seen. Entire back office seems to be held together with temporary fixes and work around. Middle managers are generally hugely inexperienced and unqualified, some regions operate with extreme pressure in almost dictatorship like culture. SMT either don't care or have lost control.