Pros
Work quality, access to world class facilities, freedom/flexibility in your projects, benefits. All the non-research staff is awesome and helpful.
Kontras
The following are for the computational research division where I worked for 5.5 years. Many researchers are quite hostile creating an unpleasant work environment. Senior researchers do not communicate with each other if they are on the same project and all the misunderstandings and issues are pushed down to the younger researchers and get caught with all the bad effects of politics. These certain senior people are not even willing to communicate properly in order to clear the situation. Some researchers are also quite selfish in terms of getting work done to benefit their own projects and do not care about anything else, including any problems or issues others may have - professional or personal. No one offers to provide extra help unless their name is going in the resulting publications. There is absolutely no professional support for career development or to understand all the politics. It's a place where you are on your own and can survive if you are good at politics, are selfish, and don't have issues with exploiting others for your own advancement and to reach higher.