People equate military service with dedication, sacrifice, drive, etc. So it is a good thing for your application if you have the complete package (decent GPA, decent MCAT, medical experience of some sort).
I mentioned briefly an experience in combat right at the beginning of my statement as it was something that solidified my desire to practice medicine. Then I moved on to other topics and spoke to my military service mostly in my ECs on the application. I wouldn't make the military the focus of your personal statement. And if you plan on going to USUHS, they will give you a whole other essay to write for them about why you want to be a military doc as well.