Pros
Mercury is an incredibly inviting and collaborative work environment. You will meet some of the most friendly people here. I did an internship here and they were all more than happy to lend a helping hand when I needed it. The collaborative work space makes for an incredibly effective work day. Not only will you be able to get a lot done, you will enjoy the process. I was able to take on roles in fields that both me as well as my manager were interested in and deemed suitable for my position. The customization of my job, while at the same time making a difference was terrific, and that is not something every intern can say. If I can take one thing away from my experience with Mercury, I can say that I the people and culture allowed me to learn more than I ever thought imaginable in an internship.
Cons
The only con I can think of is since I was an intern and Mercury being in the defense industry, I was certainly younger than a lot of my co workers. This did not bother me that much, but it may be worth saying. That being said there were other interns my age.