Pros
It is very fast paced, and you will learn a lot in a very short amount of time--if you are not afraid to jump in and get your hands dirty. I highly recommend it as a first job out of college--you'll receive a lot of support in learning the ropes of manufacturing operations and engineering, especially from more senior individual contributors. It'll seem pretty daunting at first, but you'll learn a couple of skills--namely multi-tasking and prioritizing--that will help you throughout the rest of your career. Also, it is a product you can take pride in--very challenging to engineer and manufacture at a competitive rate, yet we do it.
Cons
The creme doesn't necessarily rise to the top. Lockheed Martin is a matrixed organization--meaning the people you report to and perform for on a daily basis (i.e., program managers) aren't the ones determing who gets raises/promotions. That would be functional management, who seem to be in a completely different world. Many of their initiatives look great from their perspective, but end up wasting program budget with no tangible benefit when implemented. Of course, no one actually validates the alleged cost savings after implementation. So go ahead and take credit for something that hasn't happened yet, then move on to your next big project! If you curry management's favor by making these initiatives your priority, you'll move up the ladder; even faster if you have a sponsor in upper management. There are some exceptions, but many of these ladder-climbers don't have the respect of their peers and/or program managers. Maybe it's just this particular site, but the office politics are terrible. Coworkers will throw you under the bus for the slightest mistake, especially when management is looking for a scapegoat. It amazes me that if someone is protected, they can toss out allegation after allegation without any repercussions, no matter how many times the accused are later exonerated. Others will spend more time and effort for a job poorly done, than it would to take to actually do the job right.