Pros
Well, the ladies like a man in uniform, and you're able to travel all over the world to work in a place for 2-3 years at a time. Unfortunately some of the places they want you to go involve people trying desparately to kill you, so it's something of a trade off. The compensation on the officer side of the house is good, and you really can't beat the benefits. The pension you earn will be secure, barring the failure of the United States of America, and right now respect levels for the US military is at an absolute peak.
Cons
Promotion is dictated primarily by time in service, as opposed to actual skill or achievement--this is especially true on the officer side of the house. It is NOT, repeat NOT a meritocracy. You end up either deploying a huge amount or being labelled as a pogue who doesn't really earn the right to wear the uniform. Senior management is often very clueless as to what will really help an organization succeed, and you have a great deal of people who are working for the next promotion, as opposed to actually doing what needs to be done for the betterment of the unit.