the pseudo claims of running efficiency and injury prevention as regards barefoot running are based on some faulty anthropological observations, as i've said before. the essence of these claims is that mankind has been walking/running barefoot for millenia if not longer until hard-sole shoes came about this last millenia. prior to that, most foot wear was light, thin soled, and more supple/flexible than modern shoes/boots. furthermore, cultures highly dependent on bipedal locomotion, such as nomads and hunters, tended to be very efficient and effective running in super-light sandals or totally-bare feet. and somehow these folks did it for miles on end, day after day, and all without injury.
but remember, we only test and measure those who can and still do run. we haven't evaluated all those who live in more urban environs/circumstances who cannot or will not run, some of whom made this choice not because they didn't want to be able to functoin in their respective tribes/cultures but because maybe it hurt to run when they were young, so they pursued other ventures. those who still walked and ran a lot were better built for doing so.
modern studies, some of which i have reported on, have concluded a variety of reasons to convert to light-wt, barefoot shoe designs: efficiency due to less weight and injury reduction due to re-education and strengthening of the intrinsic, smaller muscles of the lower leg and feet are two of the main reasons people promote and/or wear barefoot shoes. some of these studies are quite good; some are less so, and many have been abused by the media hype, probably as a result of press releases sent out by manufacturers of these shoes. this study, on the other hand, narrowed its scope and kept its focus on efficiency: http://well.blogs.nytimes.com/2012/03/21/making-the-case-for-running-shoes/?ref=health
using runners who actually ran barefoot, so there was no adjustment period necessary, they had them run on treadmills with a variety of manipulations: barefoot with lead strips on the tops of their feet that were equal to the weight of a light-wt brand of running shoes, and other conditions, too. they found no significant difference bw going barefoot vs shod, with some small benefit to the shod conditions. the conclusions are tame - basically, if you are an elite racer wearing a lightwt shoe may benefit you. for the rest of us slow pokes, it probalby does not make much difference. (i've made similar claims about cycling equipment - other than possibly making for an easier ride, it probably won't make most of us that much faster; racers might benefit from hi priced equipment but the rest of would get equal health benefits riding a cheaper bike.)
but i must confess that i have been wearing merrel's brand of barefoot shoes for over a year and while i do not run, because of knee arthritis, i CAN run, even if only across the street, without pain in the knee or feet, something i could not do in hi priced new balance cross trainers. why? i think it's because barefoot shoes make you run on the ballls of the feet and avoid the heel impact, which shocks my knee real painfully. furthermore, as a trainer on my feet for several hours/day, my feet and legs don't hurt in barefoot shoes but within a couple hours, regular shoes cause my lower leg to ache. even my feet feel better despite having no arch support for my flat feet!
so what's my opinion on barefoot shoes, in light of this study? well, if you are interested in trying them even if only for walkng around your home or for other ADLs, see if going barefoot hurts....but enter this path gently. do an hour/day for a couple days, then two hrs/day, adding 30-60 minutes every couple days. after you've acclimated to them, try jogging, on flat, less dense - i.e. not on concrete or steps at first - surfaces, but start in 5 minute increments throughout the early accommodation runs, and keep them to short distance runs. gradually add distance, then start adding speed - this could take MONTHS but jumping into these kinds of shoes without accommodating them and the hard surfaces on which most people run, is asking for trouble. and nothing hurts a runner's overall psyche than foot and lower leg pain.