Pros
Federal benefits. are good. Vacation, sick pay, holidays and small pension if you stay more than five years. Also unionized. They used to hire older people. Not sure anymore.
Cons
Tax law constantly changes and so do IRS procedures. However, the IRS has not found a good way to keep front line employees updated with the latest information. Update links on their internal web are hard to find, broken, outdated as soon as posted, etc. IRS is reactive instead of proactive when implementing tax law. Call center employees are problem solvers but also on a time clock. Call volume is more important than actually finding the correct solution. People usually don't call unless something has gone wrong. Employees are often left guessing and feedback from management is slow or never forthcoming. Employees are reviewed often and highly criticized for any perceived errors. Errors are subjective by the reviewer as the reviewer can interpret procedures in their own way, and mostly never allowed to be refuted. Initiative to help the tax payer is not encouraged. Their motto is "cover your own arse or you will receive a bad review". I put up with the job until retirement age. There are good people working there but they are hamstrung by the craziness of the IRS.