Pros
Good name to put on your resume, or get an internship at. Benefits competitive with industry and so is starting salary, just don't expect for your salary to stay competitive after hiring on. Good job security for now.
Cons
The compensation does not keep up with the industry, you can expect a consistent 2.5%ish raise each year unless you are highly ranked. Salary compression is a huge problem, expect people who hire on 2+ years after you do to make more than you do after working there for 2 years. The new total comp system they have rolled out is horrible in its implementation. They have imposed set bins for ranking their employees. So during performance review with the new system new employees are typically ranked "2", which is the lowest you can be without risk of getting fired, for the sole reason that they are new and a set percentage of the work force has to fall under the 2 category. You will not be ranked higher than mediocre unless you are really liked by the senior management. The entire total comp system was implemented to break out the support staff from the technical staff and decide their pay based on the market value of their line of work. However all the technical staff are still under a single market base comparison (~80% of the work force) so all they succeeded in doing was paying support staff less and paying the same amount for research staff. If you are a low paid engineering major, such as civil, you will get paid exactly the same as a comparable chemical or nuclear engineer who typically make much more in the industry. The system also seems to be flawed in what they compare your salary to in the market, it doesn't seem to increase with experience. So after a few years HR says you are overpaid and your raises drop to next to nothing. The work here also seems to be sub par lately, I've seen some truly awful work openly presented that uses computational techniques which are just not valid for the problem of interest yet no one brings it up. Management views any criticism, even if constructive, in a negative view. Only positive things are expected to be said about others work, even if it's wrong. One of the new performance review categories is behavior, so if you critique others work you are views negatively and hit with it during performance review. There are very few negative things that can happen to you for doing poor work, if you don't deliver you are typically still ranked average and can just coast along for most of your career with little repercussions. Mean while to truly succeed you have to work weekends and get lucky with a lot of your projects to get any recognition from management, who typically have no idea what you work on. You can expect to be promoted from a Senior to a principal member in 7-10 years, no faster no slower no matter what you have done. Promotions in our center are decided by the director also, so all the senior managers have to like you before you are promoted so if your program competes with them at all or they have something against you, they will continually block your promotion which has resulted in at least 3 people leaving to go to academia or industry. Even the one who left for academia (which is typically paid lower), got a 40% raise over what he was getting at Sandia. Others have gotten raises as high as 50%, the president of the labs has stated that he has no intention to compete with the salaries of google, BP, Slumberjer, etc yet these are the companies who make up the industry so the entire total comp system is a bit of a mystery.