Pros
Extensive training (about 2 years of schooling), E-5 leadership, having unique experiences, being pushed beyond what I thought I could ever accomplish. The Post-911 G.I. Bill is great for getting a college education (especially after finishing/retiring from the Navy). On submarines, you may be able to travel based on the type you are stationed on - just do not rely on it.
Cons
Long-term there is not a lot of room for creativity; processes are very standard - and for really good reasons. Your experience varies based on the command you are stationed with. Duty rotations are subject to the needs of the Navy. I have had excellent commands for the most part, and was proud to serve with nearly everyone I worked with. Sea duty stations tend to have longer hours and are more arduous; shore duty stations vary but generally give you a better work/home life balance. Despite numerous safety measures, risk is inherent. Do not undertake this decision lightly.