I worked at Commonwealth of Massachusetts (More than a year)
Great networking opportunities, very social position, people always available to help. Easy to work remotely, learn-as-you-go culture. Great for entry level or first jobs post-graduation
Low, non-negotiable salary. Not much room to move up. Difficult for people who aren't social or aren't willing to use connections. Dealing with constituents can be difficult, can be hard to track down legislative liaisons.
I applied online. The process took 2 weeks. I interviewed at Commonwealth of Massachusetts (Boston, MA) in March 2017.
Standard questions. Asked a lot about what you are looking for and your character. Basic questions regarding how you would handle standard situations. They then walk through your resume line by line and quiz you on general knowledge of the agency. A simple google search will suffice. Do not try and drop names. They won't care once you have the interview.