Pros
Most of my coworkers were friendly. Heath care benefits are good. Low stress environment with short hours.
Cons
The organization structure is very flat, so promotions are rare. On top of that, raises are just a standard 3-5% every year. Since many of the projects are classified and for the government, the experience gained doesn't typically translate well to other fields, which would make it hard to change careers after working at ARL for any significant period of time. Dealing with classified projects is a pain. Also, many of the project are really not that interesting. Despite being secret work in defense applications, many labs at ARL just maintain legacy systems that were developed decades ago. One of the biggest issues I had was the complete lack of company culture. There's never any sort of company organized social event, collaboration between labs is rare, and the general culture is one of mediocrity - 'Just do enough to get your work done and don't complain or ask for additional work'. Pay is below comparable positions in the private sector. The pension is a ripoff for new employees. Overall, I'd recommend against working here.