Pros
The company is very good at understanding the needs of its employers and adjusting to those needs (flexible working, mental health support, able to adapt so I can thrive in the role with my ADHD). There is no social hierarchy linked to job seniority, the majority of people will gladly talk to you and provide advice no matter how senior they are and how junior you are. The company will listen to how you want to develop your career, and will do what they can to help you achieve it. A very diverse selection of projects that one can get involved with. They are based in several countries around the world. Everyone I know had job security throughout the COVID-19 pandemic.
Cons
Some systems used (e.g. recording weekly timesheets) are inefficient. They have another office location in the centre of London, but the main headquarters are in Croydon. The internal search engine to find the resources you know the company has (learning resources and sports clubs etc.), makes it difficult to find the right page. In my experience, it is very clear what you need to do to be promoted from one grade to the next, however, it is not so clear how to get a salary raise. Some sectors within the company have a very different culture, which means that the experience is uniform throughout the company.