Pros
The best reasons to serve in the Navy are pride and patriotism. Additionally, as a junior naval officer (as well as any branch of service I assume) you will have access to a lot of training in different fields, which overall will make you a more well-rounded leader. Additionally, the teamwork you encounter is unparalleled in the civilian world. You will learn from great mentors, and also, discover character traits that are not effective and unfortunately even repulsive.
Cons
Long deployments can be difficult to manage, especially if you are married with children. In addition, there are obviously career ceilings. Downtime too can be difficult to handle when you are used to operating at a fast pace and motivated to provide quality work.