A friend of mine flew for them for about a year. I went down a visited a few times so this is just second hand and my observation from being there a bit...
They have Islanders, TriLanders and a few Caravans. I think they were pretty desperate for people (dunno if they still are) so they were taking guys at low time and getting them up to 135 VFR mins.
MX was questionable at some times and it was pretty normal for them to have a few engine failures a month. Their DO, at one point was banned from being near any aircraft because of his drinking issues. I don't know if the guy is still there or not.
Vieques can be a tough place to live. There is very little infrastructure and not much to do. Also, the island has a huge crime and drug problem.
All that said, it is absolutely beautiful over there and they fly into some amazing little airports.