I am a current student at a Caribbean school, and yes they are legit. In my opinion, the schools are largely alike - you get some bells and whistles if you attend the "big four" but you also pay more than double the tuition. What they all have in common is that you have to work your TAIL off in order to make it work, and there are huge drop out rates because people don't know what they are getting into.
The Caribbean route is definitely not easy and there are a lot of hoops to jump through. I know plenty of people from my school who are now in residency spots - both in Canada and the USA. The percentage of students who make it is not crazy high, but with hard work and determination it can be done. Caribbean schools are a feasible option for people who can not get into medical school for whatever reason - and there are plenty! Everyone has their own reasons for even looking into Caribbean schools.
I have been keeping a blog of my journey so far, anyone who is considering Caribbean medical school is more than welcome to check it out.
www.drnicolefox44.blogspot.com
I am always happy to answer any questions people have about the process!