Pros
Pros and cons vary widely by department, but this is my experience. Very good pay, flexible work schedule, working from home several days a week. General freedom to get your work done the way that you want to, as long as it's done and customers are happy.
Cons
The biggest problem is that they are overall very cheap, despite my salary and good bonuses. When you're the biggest CRO in the world, it's hard to show organic growth and so you have to find ways to scrape together pennies for shareholders. This has led to a lot of offshoring, which makes it impossible to get anything done quickly as you have to wait for someone in Slovakia or China to get back to you. Benefits were destroyed this year, with high deductible medical insurance being implemented. No office perks - you get black coffee and you like it. No employee engagement, worsened by employees working from home. Constant reorganizations. Growing pains from the merger. They have reduced the number of buildings from three to two and now down to one, which means hot desks for everyone. Not much room for advancement. I haven't had any luck when applying to other departments, but switching jobs within related departments is relatively easy. No professional development. Travel or other expenses are now nonexistent unless it's customer paid.