Cape verde possibly is further behind then other places currently but it has a far better climate then many places with all year sun and best place to compare it with is the caribbean.
The most invested Island is Sal with Sao Tiago close behind and Sao Vicente is coming along also with a 3rd cape verde international airport around 8months from completion.
Property is cheap i would say and there are many companies building lots of property and also big hotel chains moving in like Rui.
I think if you want a property to rent out straight away Sal is possibly best as it has been hosting tourists for longest but if you are happy to wait it out longer any of the islands are fine except two islands which are saved as a kind of national trust site.
I would buy on sal or sao tiago
There really is a lot of money going in to cape verde as they know tourism is something the country can do well.
As for the government there are no issues with everything very diplomatic and fair and safe, and this has been the case for many years.
I really recommend Cape Verde as a great place to invest in as it is only improving and you would be happy to spend many holidays there and would easily rent your property out.
Travel companies will soon be doing package holidays there as more and more flights become available.
This is my opinion but i believe Cape Verde has to be at least sampled.