Speaking from my own personal experience (which includes some time posted with special forces folks), high time this has happened. Many of the arguments against it are spurious as well as flying in the face of what is already happening. And since I've not seen anything from women who are or were active duty, I'll share a little bit of my experience and perspective.
The default assumption is that we (women) can't do it. Period. Especially if you are petite, as I am. When I was active duty, I was 5'2, and hovered around 100lbs. (I weighed 94lbs when I came out of basic training, and *much* stronger than I looked -- being light is actually a bit of an advantage in some ways) But many looked at my matchstick arms and assumed, "Hey, I can take her!"
They found out differently when they tried. I did lift men who weighed a significant amount more than I. Threw them, in fact. (Judo is fantastic -- leverage is an excellent tool) But there was resistance. A senior person -not an officer, for the record thought very little of my physical capabilities and tried to limit me to -forex- carrying more than 15lbs on a weekly ruck. Figuring the men were carrying about half their body weight, I pretty much blew this off (with permission, I should add) and carried 55lbs instead, which was half of mine. This from the same man that I beat back to the building at the end of our hash runs, which took place in the hills. Hills that were practically vertical and covered in sawgrass, and muddy as hell. You could slip and fall and break something, easy, if you weren't careful or just shifted your weight at the wrong time. I was one of the first folks back, as a matter of fact. Now, could I do what the men did? Not exactly across the board, no. That is obvious. But would I be able to handle myself? Yes. Would I be able to properly fire and maintain a weapon? Yes. Would I be able to follow the orders of my superiors? Yes. Would I be able to save a fellow from the burning wreck of a Humvee that exploded due to an IED? I do not know. I don't know if many people know if they can do that until presented with the situation. What I *do* know is that in situations like that, both adrenaline and training is your friend. And we've all heard stories (and seen one linked here that is relevant) of women being able to do extraordinary physical feats when needed.
The point I'm making is that he assumed, just because I was female and small, that I couldn't do the most basic things, like carry a ruck for miles up and down hills or get a minor injury and still carry on, let alone do my job. And he wasn't alone in that. I caught a lot of flak from plenty of people. I came to my desk once to find a printout about how to be the perfect wife and mother, and was asked more than once why I wasn't in the kitchen, barefoot and pregnant. That was supposed to be my place. But my place was a desk job doing intel. Supporting some of those same people, providing them with information they needed to do their jobs effectively. I was and am quite proud of the work that I did, and personally felt no desire to serve in a combat position. I liked what I did, and felt that I was making the best contribution I could in that capacity, and not in the trenches. I am not a fool, however, and I knew that it was possible that I would have to either be fired upon and/or return fire. Even be killed. But everyone who joins the military is aware of that possibility and accepts it as part of the job.
I also had the very basic POW training briefs, etc. I knew that my job wasn't to not spill my guts, but to hold out for as long as I possibly could, to make what I knew and would be forced to share as operationally irrelevant as possible. So much is time sensitive. If you can just hang in there, what you know won't matter. It would hurt and be scary and I've been raped before, and so the prospect of such happening again...is not pleasant. But it's not much different than what a male soldier or airman or marine would have to face. To assume that I cannot face it or that the men I served alongside would not be able to face it and handle it if necessary seems like a grave insult to us both.
None of this even gets into the promotion aspect of things. Women officers were getting the short end of the stick there, and so for their sakes especially, I am glad to see this policy enacted. As others have noted, having women higher up in the heirarchy may in fact help the sexual assault stats we're seeing. Women *are* feeling more free to report them. And perhaps, with more women in the upper ranks, we may find more support than we have previously on issues such as these, instead of constant jokes and complaints about sexual harassment training and blank stares or half-assed investigations when there are allegations. I won't pretend that this will fix any of that. It won't make people or society at large automatically accept that women are equals and that they should be allowed to at least *try* to compete on an equal field. As far as I'm concerned, so long as high standards are maintained (and that doesn't necessarily preclude making necessary adjustments to account for the differing strengths of men and women) and women can meet those standards, then they should have the same shot as any man. If a man isn't interested in a combat position or isn't capable of performing, he's moved to somewhere or something else or even kicked out. The same should apply to women as well. I don't think that the point is to have women there as PR tokens, but to allow the ones who are interested and capable to have the opportunity to serve in that capacity. Period.