Avoid unless your priority is work-life balance.
Pros
Pleasant office environment in a central location. Subsided canteen. Opportunities to travel widely. Interesting organisation. Easy to get away with not coming into the office very much at all and not doing any work. Plenty of people in my team I didn't see week to week and appeared to do next to no work. I can not exaggerate enough the number of cushy jobs. Personally, I don't really see this as a pro.
Cons
Insecure FTC Poor management Poor leadership. Lots of people who have worked there for years and years who are under-qualified for technical jobs they are in. Complete lack of accountability for failure and waste. Line managed by day rate contractors. I had 6 line managers in under 2 years as they all left or were fired. Poorly run projects. Lack of consideration that people need job security - I would advise against taking a FTC there. They do not respect that you need notice and will not let you know if they aren't going to renew. No career progression. People progress based on being friends with the right people not on talent. Management isn't qualified enough themselves to recognise talent. Extremely hierarchical in a way which doesn't compare to any organisation I have been a part of. Very old fashioned. Senior management really appear to believe they are better than the people they manage! They do not like people below them giving their opinions. Only work here if you're prepared to keep your experience & skills to yourself! Not good if you are trying to advance your career.