Pros
The people and the projects. I've met great, smart people there. I have worked on some very interesting projects and had the opportunity to learn about a vast array of domains I never would otherwise have been exposed to. I like my immediate chain of command and find them to be competent.
Cons
A private equity firm has purchased a major stake in the company and while management promises us that there will be no significant changes in how we do business, I have a hard time believing it. It's an extremely profitable company, but obviously private equity firms are interested in making as much money as possible, so I'd imagine changes will in fact happen, and they may not be terrifically palatable to staff. There is no guarantee that you will get a good project. I know some people who have been required to work on lousy projects for well over a year.