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First off, I only have experience with US reserve military (haters gonna hate), but I have a lot of friends who went/were active so I have some sources for what I'm about to throw out there.
1. If you don't support the military or what it does, don't join. If your attitude/non-support doesn't get you kicked out, it will still get the attention of your command and they will make your life suck until you get out or to a new command (where it starts again). Even if you hide your non-support well, you still run the risk of pulling a Bradly Manning and 'doing the right thing.' Which is treating him GREAT right now.
2. Even some dogs get treated well. I know guys that love thier job in the military and have re-enlisted instead of getting out to go to school as per thier original plan. Key example: I have a friend that fixes fighter jets. He contracted into his job when he went to the recruiter knowing that when he got out he would be able to place in a high paying civilian job right away. He's re-upped twice because he loves his job, he has a stable job in an unstable economy, and where he's stationed (Japan). Yes, he has enough time for anime, D&D, vidja games, and whatever he has sex with on leave. Yes, some of the other guys in his shop have similar interests.
3. A military career will be what you make of it. There are a lot of available jobs in the military that may surprise you. Many of them translate directly into a civilian job once you get out (or through a transition program). If you contract into a job (when you speak with a recruiter, enlisted only btw) and it is something you want to do, you will enjoy it better than something that sounds "good enough" or "better than infantry." I have friends who are infantry and love thier jobs. Kicking in doors, getting in firefights, and living in the dirt is what they live for. They hate being stateside because some of these guys FUCKING BELONG in a war zone. These same guys have done well because they enjoy what they do. They get to go to cool training and have advanced quickly. All of them have PTSD, but only a couple have a hard time functioning in society. Hearing loss on the other hand is a HUGE issue for them all.
I have friends who work in intelligence that enjoy thier dorm room living style barracks with a clean and quiet work environment. Some of them keep strange hours, but it suits them. They don't tell me much about what they do, but it treats them well and they've picked up rank fast. These guys almost never stay in because when thier contract is up, guys with an intelligence background start in the marketplace with entry income over $80k/year. You need to pass strict screening for a security clearance for those jobs though.
I also have friends who went in either not knowing much about the job they signed up for or with a open contract (their job was assigned to them, they didn't pick it). Guys in this group that I know generally hated life and got out, either through finding ways out via medical discharge or by administrative separation (bad). If you don't want to be there, you won't last.
4. Reserves are a different ballgame. If you want college paid for (but don't plan on deploying), pick any reserves other than the Marine Corps. Even Coast Guard Reserves get education benefits, but not USMCr. However, if you have ANY active duty time outside of the training environment in ANY branch of reserve, it will count toward your benefits through the GI Bill (free college money).
The whole one weekend a month, two weeks a year thing is a bit of a gag though. If you do like I did and try to go to school while in the reserves, you will have stubling blocks. Every time we do our 'two' weeks per year it turns out more like three and interferes with either exams or the beginning of fall semester. Also, those weekends have a tendancy to be four day weekends. It's fun explaining to professors how this letter from my command excuses me from class on Thursday through Sunday, but due to needing to pack on Wednesday night and drive half a state away to check in to the hotel, no feasible time over the weekend, and the need to fucking de-stress and unass my gear on Sunday night before my week starts all over again means I won't be able to take that test on Tuesday morning or why I want an extenion on that big project. I've had issues with profs over this that I ended up having my command talk to the appropriate dean on campus over, and I've had professors just dismiss whole tests/projects for me.
Reserves allow you to do both at the same time, but there are a lot of challenges other than the direct conflict with school I just mentioned. It is a lot harder to work out on your own every day than when on active status and your shop/platoon/whatever has scheduled time/activities that you just don't fucking miss. Your command may or may not hate you just for being in the reserves. In the USMC reserves, our units have active duty guys running the admin/logistics. Sometimes they make life suck for reservists because they can and want to. It's hard to balance work/school/military/having a family. I do it, I know people that do it, but that doesn't make it any easier. I'm still glad I'm not active though. I place a high value on my personal time/space and enjoy having a house where I can fuck my wife whenever I want (outside of training weekends).
5. Officer life can be pretty boss. Getting there can be the hardest thing you ever did in your life. Also, (at least in the USMC) you don't get to choose your job. It's selected for you via a form of raffle based on your performance and your job preferences (which you list in decending order). This allows a rationing of performers and shitbags to each of the officer job categories so you don't end up with all the fucking rockstars in infantry/intelligence/pilots and all the incompetent fucks in supply/admin/food-service. This rationing is good for the military, but can really fuck the individual.
I know a guy who ended up an infantry officer. He even started off elisted infantry. He is everything you expect in an officer or a combat leader: cunning, capable, and vicious. The system has treated him well, but there is blood on his hands. As an officer (esp. infantry) the individual pays a very high personal cost for success of not only mission, but thier own career. I would follow this man to the gates of hell, but I know that he would pay passage through them with my blood if he had to. This leads me to my final point.
6. What you get out of the deal is a bit of a wildcard and a bit of what you ask for. It's like wishing with a monkey's paw: you get what you ask for (usually), but it's not how you intended. I wanted a lot of the personal enrichment one expects from the military and I got it. But it's not they way I imagined or expected. Leadership skills, self discipline, a mindset that allows you to overcome just about anything that comes your way, and the perspective granted by emotial trama. All things I gained. All things I expected. And as much as I may bitch about my career, I wouldn't trade any of it back.
Then again, YMMV.