Pros
Great team of intelligent, highly motivated, inclusive people working on big projects. Company has given me a huge influential project to work on even though I've just arrived. The directors/founders know your name and will take time to talk even though they're adding 10s of people a month. It's a big company but has retained a start-up mentality and culture. Free beer on Fridays, a big party every quarter at Tiger Tiger with an open bar and a boss who asks me what projects I want to work on all add up to a great working environment. They expect a lot but there's a challenging, supportive environment to make sure I can fulfil what I'm being asked to do. Great benefits and thousands of pounds in prize money every quarter to people who come up with new ideas or get nominated for excellent work.
Cons
The company needs to lose a little more of it's start-up mentality and hire more people in key areas like HR, IT etc. There's the normal amount of politics that always exists in a large organisation but I've found longer term employees to help me navigate through OK. There's not any set career progression but people are moving around all the time as they tell their managers what they're interested in.