I don't know if
@Caverject is still around, he also has recent (as in he is in the uniform right now) experience,
@giga is presently uniformed for USPHS. There's a couple with recent outs including the moderator. My general opinion is that you are an officer first and whatever your technical background is second. Don't be surprised about your assignments in certain areas. USPHS has better control over having their officers do the jobs that they are trained for, DoD, much less so. It also helps that pharmacists can read, write, and do math adequately such that they can be sidejobbed into other positions as well (and actually for flag ranks, you have to have your ticket punched for certain sidejobs).
Also, the pay and benefits work out that you get less and you often work more than 40 hours due to the administrative responsibilities of being an officer. Don't believe the marketing hype about compensation. The thing they don't hype (enough) is that while you will never get the same guaranteed level of compensation as would normal civilian life, if you intend to make it a lifer, the institution turns around and takes care of you in a way that no civilian outfit does (short of a religious institution for their clerical practitioners). You will never be destitute and without adequate means should you make it to honorable discharge retirement irrespective of your health status. (That is changing with the rule changes to the military pensioning status which is a huge screw-you to careerists but treats non-careerists much better.) I don't really think it's a bright idea to go in unless:
1. You're so desperately poor that you need the service scholarship (or you need citizenship).
2. or, You intend to be a career uniform for whatever motivational reason suits you.
3. or, you don't know what you want to do with your life (BUPERS figures that out for you if not)
A noncareerist loses more ground when they transition back from the old days. However, thanks to the market, that might be changing. Also, except for some positions in USPHS which are very technical in nature, you will eventually have to promote above your comfort level, work a job that you may not necessarily be trained for, supervise people and be supervised by someone that you cannot get rid of (you can't quit like the civilian), and you will relocate for the good of the service.
I wish I still had the percentages with me on how made it to retirement. It's an astonishingly low number and which drives the continued need for O-3 expendables. That's also changing due to the nature of the economy as positions and billets are much more competitive than they used to be, and people no longer are brevetted (in a position and rank above their official paperwork rank and job) as commonly as even a short time ago.