This is a highly undirected research environment. There are no deadlines, very flexible hours, and no clear goals. Your only mission as a post-doc is to produce papers to make the lab a success and aid in the approval of future grants. You need to be someone who is very driven and motivated about your research. Otherwise 75% of post-docs end up leaving the lab after their two-year tenure.
If you are good at reaching out to others in an environment where almost everyone is flying solo, if you are good at writing papers, if you are good at driving yourself, if you can avoid getting stuck in a slow line of research, if explaining what you do at conferences excites you, if you need to be working at the highest-levels of understanding .. then this is the place for you.
On the other hand, if you want clearly defined goals, if you aren't interested in being stuck in a single line of research for years, if you want fast-pace, if you want to feel an immediate, broader impact to society, if you want job security .. then this place is not for you.
Also, it's a government lab. So the services can't be too bad and they also can't be too good. No one wants to see government employees getting free lunch or having google-style perks. It's definitely better resources and pay than a university post-doc though.