Here's a helpful Congressional Budget Office summary of federal civilian compensation compared with private sector compensation:
What it shows, basically, is that the federal civilian pay scale reflects the relatively compressed salary distribution of yore, rather than the large wage premium for highly educated workers that's prevailed for the past 20 years or so. A working-class person without a bachelor's degree would do very well to seek out federal employment. But the rewards are much more modest for highly trained individuals. This is probably not the best dynamic for the country. It's at the high end that you really need to worry about whether the fox-catchers are getting salaries that are competitive with the agencies that they need to police, and where one has to be suspicious that relatively low paid federal jobs are valuable as training for a later cashing-in with the private sector.