Pros
Very happy at LM SSC so far (2.5 years). Benefits are great: 3 weeks vaca for new hires, every other Friday off, and off between Christmas and New Years. In general, there is a healthy work-life balance attitude. Of course, there are times that we've got to put in extra time to get things done, but that is on an occasional as-needed basis only. In general, I have felt respected and trusted by management, and I've been given a lot of responsibility. Also, working on vehicles destined for deep space exploration is pretty awesome, and a daily inspiration.
Cons
Some remnants of 'good ol boy' club attitudes around here, but LM is actively trying to become a modern, attractive company to new employees. As with every company I've ever heard of, diving into something can be a little overwhelming with limited organized training, but coworkers are generally available for support.