Pros
You'll get reporting experience that is unmatched in terms of substance and access. IWP is a well-respected inside the Beltway name -- if not with the government, then at least with lobbyists, attorneys and private sector stakeholders. It's a widely regarded stepping stone to bigger things in Washington journalism. It has a strong, stable business model. As most reviews have already stated, Alan S. has built a strong company, and in many ways it's immune to some of the economic hardships many print publications are facing today. You will learn important lessons about journalism that will stick with you for the remainder of your career. Every policy area IWP covers is interesting, and you'll learn about the tension between Congress and the executive branch in a way that's only comparable to a graduate seminar.
Cons
You're taking a huge risk by working here. If you end up at one IWP publication, your fate could end up vastly different than it would be if you'd accepted a position at another. Some editors are notoriously difficult to deal with, some play favorites, and some will berate you every day, from the moment you walk in until the moment you leave, if they don't like you. You will grow here in the sense that you could learn how terribly people can treat each other in the journalism world. At times, you might be forced to consider if journalism is even a worthy career choice, considering the difficult personalities you're dealing with and modest compensation. In some sense, though, this isn't really much different than any other journalism job. This is a job you will take home with you, regardless of any best efforts to maintain a balance.