Pros
They hire top-notch people so you will almost always work with others who are talented and motivated. Most groups are excellent at managing complex projects and there is almost nothing that intimidates the leaders who have navigated difficult things in the past. Pay is competitive and there are typically good opportunities for motivated people to advance.
Cons
Its a place where the focus is literally keeping the lights on. You're not likely to be at the bleeding edge of any discipline while working at FE. It's primarily about risk management and choosing the solution that solves the problem with the lowest potential impact. The company itself has a more traditional culture, although some groups are trying to change that and are accepting of more flexible and contemporary policies and management styles. Still, it can be a bit stifling at times and the general practice is to follow what has worked in the past rather than try something completely new.