Ok, I´ll bite
The military can seriously affect your chances at matching into a number of specialties (though it can also help with some, especially if you´re willing to do a GMO tour first). It´s not a good deal financially unless you both go to an expensive private school and then match into a lower paying specialty like IM (in which case it´s actually a pretty good deal, at least financially). The work enviornment is several kinds of unique that I´m not qualified to comment on yet, but several members of the milimed forums are qualified and have commented. Doctors are not protected from deployment, and have to move as often as every other officer. Many doctors are forced to put off their residency and serve a GMO tour, which means they do a 1 year internship and then start practicing. The amount of time their residency gets put off can be anywhere between 1 year and the length of their obligation. See the milimed forum for more information.
There are also several positives, or at least I think so (I´m doing Navy HPSP), but from what I´ve heard if you´re not at least going in as a patriotic idealist it´s probably going to balance out on the negative side of things. Most of all, make sure you understand every detail of what you´re getting into before you sign the papers. I think a lot of people feel bitter after they joined because they´ve been ´lied´to (they won´t waste a doctor on medical recruiting, so medical recruiters are not particularly well informed. Well that might have been true in the past, but now all the information you need is right here on this forum. If you sign the papers and then are surprised at what you signed up for it is now officially your own danged fault.
Also, this post is a palimdrome