I have been working at US Department of Treasury full-time (More than 3 years)
The benefits are excellent and compare favorably to the private sector.
It is very hard to change jobs to an unrelated career field in government service even if you are qualified due to previous work experience. Dress to impress, The Treasury is considered to be one of the best dressed government agencies.
I applied online. The process took 4+ months. I interviewed at US Department of Treasury.
It is lengthy. I can take anywhere from 3 to 9 months to get onboard. Starts with a phone screening, then you come in for a panel interview, then you do a one on one and then you are notified on your selection.