Pros
If you are an average software engineer it should be easy to maintain employment here. It is not a hard job. Low level managers are a mixed bag, but I got a really good one. And my department had pretty good management (E44). I was given the breathing space to learn quite a lot on the job and get much better at certain aspects of software engineering.
Cons
Most people who work at Newport News Shipbuilding are not engineers (less than 20%). And most of the engineers are not software engineers (less than 20% again). Thus, software engineers are tiny portion of the total workforce so the company culture is dominated by people who are clueless about what good software engineering looks like. Therefore, it is common for low-quality software engineering practices to persist for decades unimpeded. The engineers at this company, software engineers included, are below average. Worse, they are complacent in their mediocrity. You can try to raise the standards if you really care about quality, but it will be an uphill and lonely battle. And it will be a political battle, where you will be more successful the more gregarious you are. I never got punished but I have been taunted and ridiculed by engineers for trying to raise the standards of my work if it require them to do anything at all. The pay is below average. But this makes perfect sense with everything else I said above. Pay and performance culture go roughly hand-in-hand. Below average pay nets below average engineers. Finally, for software engineers, the Navy (NAVSEA) isn't good at software. They often don't understand what best practice software engineering looks like and don't care. This can end up being a real impediment to the career growth of software engineers as NAVSEA sometimes oversees the creation of software tools that software engineers are required to use, but the tools themselves can be quite bad and not marketable (NNL often creates them).