Pros
Benefits. Great cafeterias, free coffee/tea, nail/hair salon, gym, company events, continuing education -- best I've ever experienced.
Cons
Major league backbiting and politics. I worked for a very strange and fairly new department which will go unnamed. Very intelligent people, but oh-so lacking in reality. No professional savvy with the group I worked for and most of the people either kept to themselves or paired off with a few others. You won't be 'let in' to the group. Don't even try to ask for help ... you are pretty much on your own. The person who ran this unique department had major ego issues ... most of them did. They use Gmail as their company email platform --- odd, odd, odd. If you are a contractor, your chances of being hired permanently are quite slim, regardless of what recruiters tell you.