Pros: Good benefits intelligent people
Cons: Not secure, bureaucratic, little guidance
You better make sure you are an expert at what you're applying for before you accept the job offer. NREL only hires the best, the flawless, the ultra-intelligent systematic super humans.
There is little training and zero to little mentoring for your specific job. You are expected to learn quickly and independently, without much guidance. Most people are willing to help, but your manager will most likely be informed and irritated if you are continuously asking for help (even if it's a new type of task). Don't put your trust in everyone, because if they do not like you or are unsatisfied with what you are doing, they will tell on you like a tattling child. If management decides that you are not performing to their expectations (they are usually so busy, they don't actually know what you are doing half the time and go by what others tell them), or you are not intuitively catching on to the functions of federal government fast enough, or your manager doesn't like your personality (combined with pointing out every flaw and not praising the positives), they will fearlessly terminate you without warning.
Make sure you treat your managers like superiors and always act professional around them.
Treat everyone with respect because they all deserve it.
Read about NREL's programs and research in your free time (after work because you won't have time while you are there) to become more familiar with everything, but don't report those hours on your time sheet.
NREL highly values education, so the more you have the better.
Dress professionally, act professionally, do not share about your personal life.
On the plus side- they have great benefits and everyone who works at NREL is extremely intelligent and an expert in their field.