Avantages
The company is American owned and this means they can be extraordinarily generous. They encourage your personal development and there is always someone willing to help when you're getting a bit snowed under.
Inconvénients
As an American company, they expect everyone in the UK/EU offices to behave as they do in the USA. They would typically ask 'who's your best friend?' and be a little surprised if your answer was somebody you didn't work with. The USA office works long hours and will expect you to do the same, (even though they also take long lunches and will spend time to chat with each other over coffee). In the UK it's more typical to arrive to work, work hard, work through lunch and then leave on time having achieved your targets for the day.