I've written words to these effects in the milmed forum before. I've become much, much less enthusiastic about HPSP over the last 5-10 years, and here's why. Mostly it comes down to issues after you've finished medical school.
1)
It's more or less impossible to predict what military residency opportunities will be like in 5-15 years, which is the time frame you're looking at. You may be thinking anesthesia now, but most of us change our minds about specialty during medical school. Even if you carefully look at the military anesthesia programs as they are today, it's a significant gamble to commit yourself NOW to training there many years down the road.
You're a pre-med now, so med school graduation is 2015 at the earliest. 2016 you're done with internship. Depending on which branch of service, and annual circumstances beyond your control, there is a good chance you'll end up spending 2-3 years doing primary care as a GMO. Now you're starting residency in 2018 or 2019 ... finishing up your CA3/PGY4 year in 2021 or 2022.
The overall trend within military medicine has been one of downsizing and outsourcing. Tricare has been an unmitigated disaster for training programs; patient volume and acuity (ie, how sick the patient is) have declined. Most programs in most fields have compensated for this by adjusting residency class size, or by including "out" rotations at other institutions. Some programs have been largely unaffected and remain very strong (FP training, for example). In general the surgical and procedural specialties are the ones that have been hurt the most.
I got very good training in anesthesia, but 9 of my 36 months from CA1-3 were at outside hospitals. Which was fine - I think it's even a benefit to some degree to work in multiple environments, but the travel and 'guest' status kind of got old after a while.
2)
The military residency system is a much smaller pool, numbers wise, so there is far more year-to-year variability in competitiveness than in the civilian match. Rarely, this is nice, when more competitive specialties are easier to get into. More commonly, it just means specialties that are modestly competitive in the civilian world are extremely tough to get in the military. EM and anesthesia are the poster children for this phenomenon.
3)
The military doesn't need a lot of radiation oncologists or pediatric endocrinologists. If you change your mind about anesthesia during medical school, as the odds say you probably will, what happens if you choose a field the military doesn't need very much (or at all)? You'll probably spend your payback years as a GMO doing primary care for an operational unit, then get out of the military, and do a civilian residency. There are worse things than being a GMO, but even under the best circumstances, it's a multi-year delay in training.
4)
If you end up in a high paying specialty, HPSP will be a large financial loss in the long run. A few primary care specialties may come out ahead. But you don't know what specialty you'll end up in.
5)
FAP is a way to get some financial support during a civilian residency after a un-sponsored medical school, in return for an agreement to serve on active duty after residency. This leaves all control in your hands for where and when you do your residency. It's probably a better option if you want to join the military.
6)
Don't join the military if you don't want to be in the military. The milmed forum is awash in people who joined for the tuition money and hate their lives. If you don't want to be in the military, don't join the military.
7)
I've been basically happy with the Navy. Part of that has been luck. I also came in via USUHS not HPSP, and my intent from the beginning was to be career military. I was able to embrace a GMO detour with Marine infantry while others in my position were miserable, and some military-isms that are intolerable to others are just annoying hassles to me.
It makes me kind of sad that I've become something of an anti-recruiter for HPSP. There's plenty of blame to go around. I just think that there are better options if you want to serve.
