Pros
Nice office Good location Good benefits Some great people who are life friends Good learning budget for courses to grow your career Social - good opportunities to socialise with your team and different teams at events (drinking if you like this) Culture - is a doubled edged sword - pros are that it's quite entrepreneurial, you can do what you want if it adds value, quite flat, everyone has a voice, there are good budgets to do what you want to do, the founders were sometimes seen in the office.
Cons
Culture - is a doubled edged sword. All the cons are related to the culture. Lines of job description can be blurred, anyone can start to do part of your job and you part of someone else's, without prior discussion. Low transparency. It wasn't uncommon for conversations and decisions relevant to your area of work to go on in secret. Then get approved by someone senior in that persons network without any collaboration from relevant people. High level of office politics, you need to be good at networking as it's about who you know in and out of the company, The first time I met my boss they informed me who their parents are, at the time I wondered why this was relevant. Some bullies in leadership in London office. Masculine. If you're a woman then show masculine traits to progress. Cliques and groups in some teams. The only place I've worked where people crying is not uncommon. Being brash, loud, fast and confronting is seen as authentic. Swearing is normal and shows you're passionate and often heard shouted by some people across the floor when conversations get heated. Not very diverse, mostly white men. Lots of change and rounds of redundancies are common. There are some people in senior roles who have been there a really long time, kept on as the founders and other senior people like their personality but they add little other value, the quality of what they actually do in their role is poor, they are not easy to work with and you just have to indulge them. They are still hanging around as they wouldn't be able to find employment elsewhere. Social events have strong focus on drinking (if you don't like this)