Pros
Work/life balance flexible hours Really nice, good, smart people low stress Good place for a young, starting engineer (Re-evaluate after 5 years and possibly leave then, if not sooner) Also good place if you just "want a job" to get a paycheck to focus on your life, be a "yes" man, not want a lot of stress, and dont really care about career/skill advancement. But be aware this will not last forever and when cutbacks happen, you might get surprised.
Cons
No communication by middle management Very passive/aggressive middle management Difficult to get promoted or get good raises; no bonuses Performance review system is awful and lots of "surprises", so be careful Very big and you are "just a number" False sense of job security Skills and job satisfaction can erode around 5-10 years; dead-end easily; hit a glass ceiling; Can get boring after a while Very little and/or inconsistent effort by management working with employees for career advancement or placing people on new projects once a project ends; In recent years, you will get a few weeks notice to find a new job in the company or relocate, or else they will fire you - career development at Lockheed very "sink or swim". The immediate people I work with and for were great for the most part. I used to like the open-door policy and honest communication by managers there, but things have changed fast in recent years and it is no longer a good place to work in my opinion. Cutbacks in defense industry in recent years are not good either and have not helped.