This is a big topic on the Military Board, and I wasn't sure how people not directly affiliated with the military feel about it, so I thought it would be interesting to poll.
Let's see if I can summarize without offering too much of my own opinion...
The military puts unusual constraints on relationships. A soldier typically cannot live off base unless he is married, and a significant other is not allowed even to visit base unless accompanied by the service member if they are not married (at which point, the significant other receives their own military ID card). Additionally, it is incredibly hard to set a definite wedding date (usually impossible) because training schedules or deployments change, and the military doesn't care if you have something planned. So brides often end up changing their wedding date at least once, if not several times (you typically put clauses in the contracts with the vendors that you won't lose money to change dates if the military commitment affects the wedding date, but it's still a massive hassle). If a soldier deploys, their significant other cannot be involved in the wives support groups, which typically meet on base, unless they are married (and thus the spouse has access to base).
When you are married, the military pays an additional stipend for housing so you can live off base with your spouse, they cover health insurance for your spouse, and you get paid slightly higher as you have a "dependent". Also, the spouse will be relocated with you.
Because of all this, some soldiers choose to JOP at one point, and then later have a vow renewal that functions as a traditional wedding (complete with white dress, cake, etc.). Some of the soldiers let family and friends know that they have already gotten married legally by JOP, and that the vow renewal is functioning as a religious or cultural wedding in front of family and friends. Some of the soldiers opt to keep the fact that they got married by JOP a secret and have the wedding day (with white dress, cake, etc.) without letting family and friends know that they were already married, yet they let the military know they're married as soon as possible so they can get the benefits for a dependent.
So, what do you think?

