Good to ask now...
... all these questions, while you are still young enough to prepare. Basically, it boils down to this:
Are you prepared to take a bullet, or someone else's life, for your country. I don't mean the current administration, or the next. But your country.
Pay, living conditions, image, etc. is secondary to that one question.
Now to answer some of those questions from my viewpoint:
USMC is the least thought of as far as being good for your money making plans in life. It can be done, and you can benefit greatly from the lessons taught, if you let yourself.
USMC is the first thought of for being a kick butt regular branch of service. Not counting Special Forces, the Marines have a tough reputation. It is well deserved. All that stuff that MilDot was complaining about stems from that. All reputations suffer more from one bad mark, than from 10 good ones. From resturaunts, to people, to the military, it is a truth. If the Corps can get the individual Marine to uphold everything about the Corps high in his esteem, he won't do things that mar its image. Image is important today for two main reasons (although there are more... much more)
1. The missions of todays warfighters are less about combat than winning hearts and minds.
2. Their budget (as stated before) is given to them by another branch, not the DOD directly. Not bringing the Navy down is key to their budget concerns. Civilian control of the purse strings means that we had/have to be that image to ensure we got/get our due!
Like I said there are more reasons, like pride in your work, self esteem, etc. All important. Watch people in a VA hospitol. One of the nurses there, two years after I got out, commented to another as I was walking up "He's a Marine." "How can you tell?" the other asked. "Look at the way he walks," she said. Part of the pride instilled is to overcome the downfalls compared to other services. We take pride in "doing more with less."
The main thing that matters to most Marines, however "OOH-RAH" they are, is each other. It was never supposed to be colledge, a vacation, or a summer camp. It was meant to be a fighting force that was mobile on the ocean's first, then the oceans and the air. Shock troopers, First in Last out, America's Emergency Force, all have been used to describe todays Marine Corps. While the Army was originally supposed to be the conquering/occupation force in traditional Military thinking, the Marines are the quick reaction force. Two totally different roles. That is changing as the Army has had to shift priorities since the enemies have changed. The Marines mostly have seen the world change to their style of combat, instead.
There is no shame in any service, however. It all depends on what you want when you get out. If you desire to know that there is nothing that can stop you if you just put your will behind it, go Corps. They pull that out of you, if you actually do desire it. Sure there are a lot of people who hate the life and start thinking about getting out after the first week. It is not for everyone. It's not supposed to be. It is a volunteer Military, so the people there need to love it. I would still be in today, but being a single dad is not conducive to Mission Accomplishment. I could have stayed in (and would have if there was another way), and shuffled my kid onto someone else, but she was my responsibility, and I could not be her parent while deployed. But I will never regret it and had some of my best(and worst) times while I was in.
Semper Fi.