Pros
A fun culture, people worked well together and enjoyed each other's company in my department. The informal nature of the working environment allowed it to be less stressful. I felt everything was very well organized and there was a purpose behind everything. A lot of very smart people work here.
Cons
I worked as a contractor, almost half of the company are hired as contractors. Some become permanent, most don't. Contractors do not receive the same benefits or treatment as regular employees, for example contractors are not allowed to go to certain events, which is awkward when a large portion of a department are contractors and they aren't allowed to attend something the rest of the department is, which always happens. The other thing is sometimes contractors will suddenly have their contract cancelled early for no seeming reason or explanation, just poof, and they're gone. They are also not always treated as nicely because they are so disposable so common courtesy and respect will sometimes be absent in communication. Not always but it happens.