Prós
At Lockheed Martin, we work on products that are of national importance. Lockheed Martin is a very large corporation with opportunities to work at various locations in the U.S. and abroad. Lateral moves are easy, vertical moves are much harder. It is a very political business/company, so applicants beware.
Contras
Large defense programs can be slow and it takes a lot of experience before an employee truly adds value to a team or organization. This is extremely frustrating for entry-level employees coming straight from college where performance and recognition are virtually instantaneous. Salary and salary progression are very well matched with other large defense contractors - you probably won't "cheat" the system and get paid outrageous money, but you also won't be left behind with zero percent every year.