I've been working as a military nurse for almost a year now and it is a lot different than working on the civilian side. Nursing wise, your patients are all fairly young since the average age is in the low 20's and that goes for if you're working in the ICU, ED, or labor & delivery. Your patients are also, from my experience, a lot more appreciative of your care and want to be as healthy as they can because their lifestyle (and job and income) depends on it. This is what I love most about my job because where I did work as a nurse in Baltimore, most of the patients were in and out constantly and had no desire to get better by working for it. Wherever you work in the military state-side, you'll work alongside civilian nurses, and the ones I've worked with have all been great.
Everyone's military experience is incredibly different. It's amazing, when you put on the uniform the first time, how much family you automatically get, from strangers on the street, and anyone who's served or had friends and family who served. It's a big responsibility, and as an officer, you'll be held to the highest standards at work and in your personal life. It's a dramatic change to your friends and family when you tell them you've signed into the Navy for 4+ years and you'll be moving away, especially if you're family hasn't grown up in the military lifestyle.
Every Navy nurse's experience is different too. You'll get to put in a "wish list" of your top three choices of where you'll want to do and you may or may not get them. Career-wise you'll start at a large hospital, San Diego, Portsmouth, or Bethesda, or a medium-sized like Jacksonville, FL, Pendleton, Pensacola, Fl and a ton more. And between those, your experience will differ more by if you are on a Navy or Marine Corps base.
I'm currently on a Marine Corps base at Camp Lejeune, NC and the population is a lot different than the Navy. They're a little tougher and rougher but most of what goes on at this base is a lot of artillery and field operations while the guys prepare for deployment and come home and get ready for another. You could also work in a hospital that has Navy, Army, and Air Force healthcare all together. Right now I'm working on a maternal-child-infant unit where we take care of postpartum moms and babies and getting ready to go into labor & delivery. That's one area where you will end up having to work at least once in your naval career because that's what happens on the home front and is a requirement if you want to be stationed overseas.
Military life is definitely different and can be difficult. As long as you're open to change and can be flexible, you'll do fine. There are a lot of prior enlisted nurses that went through school and will be able to help you at ODS with ironing and getting the uniform squared away. They were all my best resources while I was there. ODS is 5 weeks of very long classes during the days and learning to wear and take care of the uniform and military customs. There's no real hard physical training if you're in shape when you get there and can pass the physical readiness test. It's a lot of long and early days until the last week.
And also, the reality of being a Navy nurse is that you can be deployed to combat areas on short notice. There is only a small percentage of nurses deployed at one time (I think a little over 5% right now, with deployment stopping because of the furlough of the USS Mercy and USS Comfort). It was very weird, and still is, for a grown man that ranks as a Chief to have to salute me, when they've been deployed many times and have much more chest candy than I do. The military places a lot on your degree and credentials.