Be prepared to have all of your hopes and fears of a government job completely confirmed.
Pros
Golden handcuffs. It's easy to get them on without even realizing. If you're a young lady or chap working your way up, you'll quickly find that your salary and skill set doesn't necessarily translate with the private sector, making it hard to leave. You'll also find that the 8 hour day (or earning extra time if you stay longer that can be used for vacation) gets pretty cushy. Once you're in, you're in. It is hard to get fired and pretty stable with great benefits -- so why would you leave? You are surrounded by about 1/3 of people who are just as dedicated as you. They are hard workers, passionate and love their job. Another 1/3 of folks come in, do their work, do it well, and head out. Nothing more, nothing less. The last 1/3 are dead weight. They are road blocks. They often do more work to not work than actual work and make it difficult to get things done--some of them will be making way more than you despite your hard work. If you can accept this phenomenon with a zen attitude, welcome to your new, lovely federal job.
Cons
The biggest issue with government is the system itself. The system was built to prevent political appointees from clearing shop every four years. While necessary, it goes a couple steps too far. Additionally, everything is so prescribed and dictated by endless regulation and policy, the flexibility needed to keep America's largest employer (Federal Government) nimble and responsive to the times is almost impossible. You can work as hard as possible or do little to nothing at all. The best you can get is to keep moving up your prescribed grades and steps and an occasional "bonus" in the hundreds at the end of the year or an early step increase. The worst you can get is a slap on the wrist--highly discouraged because you can give your manager endless paperwork and grievances to deal with when that happens. Most of the time you will just be left alone. When you are looking to start a career as a hard worker. This structure can be very limiting, especially in a time of harsh budget cuts and hiring freezes. If you're in a position that is a GS-11 and not what they call a "laddered" position that can allow you to move up grades, you have to apply for another position to get a raise. This means tons of good people have to leave their job in order to be promoted. The system requires it. Meanwhile, the folks that are happy doing little to nothing in their position can hold it with little required of them for literally decades until they retire. Often most of the risk takers in government needed to keep the agencies nimble end up leaving because of these heavy restrictions and lack of rewards.