Well, a search for “Puerto Rico” plus my Dopername and that of KarlGrenze should provide you plentiful details, some promising and some cautionary, both as to a visitor’s situation and for a more longterm relocation as to the economy.
You probably already know it has changed quite a bit since '64. Still, there is a decent if smallish community of Anglo expats and retirees who have figured they get the best of both worlds, staying under the US flag while going to a place of a different culture. It’s no longer quite the low-cost-of-living locale it once was – I suppose it’s manageable if you’ve been wise about your nest egg, or if you’re into the frugal life, but housing prices indeed went into lunatic mode here also in the 00’s, and only the housing bust and a nasty economic contraction has put the brakes on it.
Weatherwise we haven’t broken past the mid-90s air temperature since records exist. However if you happen to be inside the San Juan urban center, well, all that concrete and asphalt and rush-hour traffic makes a nifty heat sink (and, is where the crime mentioned upthread tends to be; then again it IS an economically depressed urban-industrial center). But why would you remain in there if you don’t have to? Of course variations in humidity can affect the experience as well but we seldom have air just stagnate and hang like a wet towel on us (like I experienced in DC); you do know we are in the tropic and what that means for half the year, but the Carolinas are no strangers to hurricanes.
Medical facilities, if you have Medicare and a good Health Care policy, are fine quality- and cost-wise in urban centers – there, you may have a bit of a conundrum, as we earlier badmouthed our urban centers as hot, congested and rough 
. You may have a bit longer wait times at the doctor’s office or at admissions though, since the supply is struggling to keep up with the exploding demand of our own aging boomers (and the generous local HCR promises of our politicians), plus the attractive salary offers from stateside employers (we’re a net exporter of MDs and RNs to the rest of the US). If you are indeed strictly Anglophone you may want to make sure you do remain close to the major metropolitan hospitals in case of need for an ER trip in the middle of the night.
Locally-procured health insurance rates are significantly lower than stateside (as long as there’s no PEC issues or such); Medicare and Medicare-supplement benefits and plans exist or have a local equivalent and coverages are almost (but, not quite) identical to stateside. Being US territory, a citizen from any other State can just assume permanent residency; if you’re fortunate enough to have health insurance as part of your pension benefit, or VA/Tricare benefits, you just go ahead and use it here after a little bit (…OK, a considerable bit) more paperwork.
Though we do have a significant proportion of bilinguals, the entire society from government to commerce to academia is set up to function in Spanish. So someone thinking of relocation should take that into account, you may need to weave yourself into a “virtual enclave” of the network of fellow Anglos and Angloaccommodative businesses and institutions, which seem to be doing OK.
More as I think of more things…
