Pros
Work-life balance, decent pay and benefits, relatively easy job, somewhat interesting work, supportive co-workers, and absolutely the best job security out there.
Cons
Dysfunctional agency with clueless leaders that play a losing strategy with Congress trying to get more funding but only drawing further scorn and in the process destroying employee morale (the job has gotten far too political and most employees want no part of that). The work-life balance is about as good as you get, but the trade-off is lower pay and chance for advancement. The employee evaluations here are arbitrary and you will not be rewarded for superior performance. For these reasons, ambitious young workers should look elsewhere. On that note, everyone I knew there had a "just gotta make it to retirement" mentality - this is common in probably most jobs but I believe the IRS has a disproportionate amount of these types. With the budget the way it is and possibly getting worse, those who haven't already advanced to high grades may be better off somewhere else (all such individuals I knew were actively job-hunting outside the agency).