Pros
I enjoyed working at the projects I've been and the people I've met. Their benefits and COLA are incredible, and they are very generous when moving between projects and during their annual meetings. Standard pay raise once a year (5-10%) based on performance. Performance is measured by whatever your team lead/project manager says and/or observes. This can be a pro or a con. Overall, if you don't mind selling your soul and well-being for a few years I think it's a good gig!
Cons
No title change for as long as I've worked at FAST. May not matter for some people. Many of the work events are focused around alcohol. In my experience I have not feel pressured to participate, but some events are fun like mini-golf and hiking. Like many others on here have mentioned, there is an OT culture that basically destroys any work/life balance you desire. If you're on a production support site it's a lot more chill, but can be chaotic trying to meet deadlines. I've known people who have worked 80-hour work weeks. Most sites do work in C#, but pray you do not get placed in a site stuck in VB.net lol. There's also quite a bit of SQL involved. Libraries and repositories have some semblance to modern software architecture, but everything is proprietary. Many of the skills you learn while working are soft skills at best and are not very transferable once you leave. As much as I hoped it would be the opposite, there are times when it is 70% consultant and 30% software development. You are at the mercy of local government politics.