That is such a difficult question, because there is so much to think about either way. If you do get married before he joins and/or deploys you will be entitled to the benefits he receives. You'll get help with housing and you'll have help from your community at large if you encounter hardship.
It is true, however, that military families have their own unique set of challenges. When he's away you will miss him, worry about him and have to do everything on your own as far as day to day operatons in your home and family. Of course this would be the same whether you are married or not, but if you were married there's programs in place to help spouses. You would have to decide if you can withstand that type of sitution and also must consider the changes that occur when ome comes home from a deployment. It's not an easy life at all.
So if you're sure you're going to marry him either way, i would think it better to get married before he enlists so that you can be better taken care of. If you aren't sure there really isn't much advantage to getting married just for the sake of being married, since this life isn't for everyone by any means.