Right now the research doesn't show if five fingers are really all that beneficial. Over the long term, you will stretch out our ligaments in the metatarsal region of your foot. This in turn will increase the space in between your metatarsals, and could result in calcius deposits forming in between each joint, and could cause serious problems when you reach an elderly age. This is all speculative though-research should be coming down the pipe soon. I highly recommend you see a podiatrist, or pedorthist before committing serious time to walking barefoot, as many of us did not grow up walking without shoes most of the time. As a result, our feet are "conditioned" for footwear, and a radical change like that (going from shoes to barefoot) "could" be detrimental.
As for me, I have a flexible arch that results in a 3rd degree flat foot-the worst you can have. I've also got Plantar Fascitis. I wear five fingers, but ONLY at the gym or during periods of instruction. If I wear them for too long, then I get problems in my metatarsals for a few days. As for my education, I'm a certified MCMAP instructor, and am currently working on attaining a Certified Strength and Condtitioning Specialist cert. Seriously, ask an expert like a podiatrist on their take. Too many companies out there thrive on snake oil.