Although med schools turn out physicians of all varieties, there is no doubt that certain schools have their niche (primary care, surgery, research, etc). USUHS has a niche that is reflected in the school's motto: "Learning to care for those in harm's way." This is also reflected in the uniqueness of the curriculum.
To answer the original question ("Is it any good?") my answer is "yes" based upon my interview, visits to the school, and interaction with the students. I am in a position that I have frequent interaction with USUHS students, and I have been really impressed with the feedback I get from the students regarding their satisfaction with the medical education they receive. Over the last 2 years, I have met about 20-30 USUHS students, and nearly as many USUHS grads. All of them had positive feedback, and they all encouraged me to pursue this route.
I applied to 8 schools, but I only interviewed at my top 2 (I was accepted pretty early, so I didn't bother with the rest of the secondaries). My top 2 were Ohio State and USUHS. I spent 4 years at Ohio State as an optometry student, and I interacted with med students all of the time. I held the medical program in pretty high regard, because I knew some pretty smart people from OSU med. However, I can say that USUHS students seemed to have a more positive attitude toward their education than OSU students did. Don't misunderstand, OSU turns out fine physicians, and they have a great med school. (Maybe it's just that USUHS students are happier not being in debt?) I also found that my OSU interviewers didn't seem all that interested in "me" and were going through the motions of an interview (poor eye contact, cookie cutter questions). When I asked questions about the program, they looked at me like I was speaking a different language. USUHS felt like a more sincere interview, and I got the feeling that they really understood why I want to do this and why I was there.
In the end, my decision came down to stay in the military v. get out (I am active duty Army). If I decided to stay in, I wanted to go to USUHS because I have a lot of confidence in the education (the medical education in general and the military-specific education) and the students' quality of life. If I decided to get out, I would go to OSU. For me, I didn't want to do HPSP because I was more impressed with USUHS, but I don't think I would regret going to OSU if I were not staying in the military. It all comes down to what you want to do with your medical degree and where you see yourself in the next 10-20 years (sorry for the cliche). If you think military medicine suits you, I don't think you would be sorry if you chose USUHS.
I know that my situation cannot be generalized to everyone's situation, and we all have different goals, motives, etc. Nevertheless, I hope this information helps.