Pros
Exciting work! You are protecting the nation which is very fulfilling. Job security is excellent. Great health benefits, retirement options. Lots of opportunities to attend conferences and other kinds of training. Work/life balance is terrific, as well. You can work just about any kind of schedule you want, ranging from 8 days every 2 weeks to 10 days every 2 weeks. You are unlikely to ever work over 80 hours every 2 weeks. If you are in such a position, you will be compensated accordingly, but moving throughout the agency is easy so you can really decide what you want to take on. If you want to climb the chain, it used to be that seniority got you ahead. Now it is more based on performance, but we will see how the pay bands end up working out.
Cons
Pay could be better - with the new pay banding system, it is possible that employees may be paid less than in the past, but they also might be paid more. There are still the same caps that existed before, though, which means industry should pay you more. Also, the educational opportunities are becoming more limited. There used to be a program that you could take a year off to study for a graduate degree which is now eliminated. There is still a program that allows you to spend half your time studying, though.