@Jon Holdman
This is very complicated question but I'll try my best. Foreclosures are going crazy right now. There's a lot. If you can buy and hold then it might be a great investment opportunity. The problem is... hold for how long? I'm Puertorrican and I moved to Houston about 3 years ago but I listen to local PR radio everyday and stay very updated in the current situation. The main problem is that not knowing what the US Congress will end up doing, you have no way to determine how long this will go on and how many more citizens will migrate to the states decreasing population and hence potential tenants. It might take 5 years for the economy to bounce back or it might take 20, no one really knows. Uncertainty is the biggest problem.
Lending is pretty much shut from local banks and in PR as far as I know (and I'm doing more research on this) the law in PR doesn't allow for private investors to be on the Deed and use that as security for a note. So it's either your own cash or using private money if that person is willing to lend without having a Warranty Deed on the property and being able to foreclose on you.
Puerto Rico is very, very tenant friendly. Laws have change somewhat in the past 10 years but still an eviction can take 6-12 months and tenants have a lot of rights that protect them specially if there are children involved.
As far as good/bad locations... it is very difficult to tell because there are bad and good areas pretty much everywhere. As a rule of thumb, San Juan Metro has more crime than the rest of the island just like any other metropolitan area in the mainland. If buying a house, you would want to focus on subdivisions with controlled access (somewhat safer). If buying a condo/apartment (in PR we don't make the distinction like in the states) I would stick to Condado/Isla Verde/Miramar in San Juan since you can rent it to tourists as well as locals.
Hope this helps.