I did HPSP because I came from a military family and had an itch to scratch. My ADSO will be up soon, and I will be separating. I don't regret my choice based on what I knew, but I would not make the same choice today. The BS factor in the Army is bad and getting worse every day. From what I know from my Navy colleagues, it's worse there. (I do not know many Navy folks so take that line with a grain of salt.) The extra pay is not worth the complete lack of freedom to make any choices. I think it's gotten worse than it was 10-20 years ago based on stories from my mentors.
I'll add this fact. Traditionally, the military seeks to keep 25% of its MC officers through O-6 (this is widely discussed when they changed pay structures as part of DOPMA decades ago). Today, I can only think of one of my O-4 counterparts who might stay in to 20. 25% retention will not happen. All of us joined for the right reasons and were/are willing to make sacrifices but none of us enjoy the daily nonsense. I didn't mind deploying for nine months, but I hate the constant taskings to places like NTC, GS staffing issues, "accountability," idiotic productivity measurements, neverending training, and poor leadership, among other problems. There is no stability and it's not worth it.