Pros
Sense of duty and responsibility. We are tasked with taking our most expensive and important national assets out into the ocean and disappearing for months at a time. Furthermore, as an officer we're responsible for everything that happens on board. Nothing happens without an officer's permission. We are the subject matter experts in operations, from the simplest chemistry sample to the most complex nuclear launch. So with it comes tremendous pride and ownership.
Cons
I could have a few drinks and go on all night. The operational tempo is unsustainable, the administrative burden is crippling, the level of knowledge requirements are sickening. I frequently work 120 hour work weeks while in port, and underway I struggle to squeeze in more than 4 hours of sleep a night. There is always someone standing over your shoulder writing down a list of everything you're doing wrong. Then we spend the next two hours after all-day trainers talking about how much we suck at our jobs. The pay is inadequate. My family is comfortable, but the pay isn't nearly enough to justify the daily struggle. I could go on, but that hits the big things.