Retired 12 years. Don't live near a miltary base. Had Prime for the first couple of years. From my perspective, it seems the further you are from a military town, the fewer doc's there seem to be in the Prime network (especially specialists). Depending on how far you settle from a mil base, might be OBE anyway. I believe Prime is being phased out this fall for persons living further than xx miles from a mil base (40??). Don't take my word for it, please check. Tricare Standard/Extra has worked well for me ("free" broken promise notwithstanding). Only in one semi-big ticket year did I come close to the annual cat cap. There are commercial Tricare supplemental insurances available as well (MOAA, VFW, etc), should you be interested. Haven't had a problem w/docs not taking Standard/Extra. I believe the rule is if they are taking new Medicare patients, they will take new Tricare patients as well. Again, don't take my word on this.
Prescription program is good. Especially mail-order, especially generics.
YMMV.
Good luck on your retirement, thank you for your service.
Cheers!