This is certainly interesting …

… A Don’s Life: Citizenship for sale.

But the general advantage you would get from your investment seemed pretty clear: in just a few months, you get visa-free travel to a large number of countries, including the EU. This is the St Kitt's list. Nationals of some countries are banned from these investment deals (if you are an Afghan citizen, don't get your hopes up), and there is due diligence on criminal records etc, but it's an easy way if you are from China or Russia or Sudan of getting a 'free' pass around the world.