Interesting, rewarding work with good career prospects.
Pros
Lots of different areas to work. Plenty of opportunities to take on responsibility and new challenges. Generally well rewarded with good pay and benefits. Good sports and social scene. Possibilities for international work and travel. Good training and development.
Cons
Long working hours quickly become the norm at certain grades and rightly or wrongly promotion is more difficult if you're not in the office late. Some dead wood, but definitely on the decline. Responsibility and extra work comes before the pay rise and promotion. Weak leadership and lack of decision making. Too many meetings, never enough progress. Trying to get things done quickly is difficult and can be frustrating to achieve. Inter-site rivalry, even in the UK, never ceases to amaze me.