These are hands-down the most comfortable shoes I've ever owned. The fit is true to size. I found there to be no break-in period as with most shoes. They fit perfect right out of the box and I found there to be no pinching or rubbing anywhere. When wearing these shoes out for running and walking you will need to, especially on off-road trails, pay more attention to where you are stepping. As these are "barefoot" style shoes, there isn't as much sole to absorb the feeling when you stomp down on a rock or root. I don't count this as a negative, in fact these shoes are exactly as advertised. :)

The only con I can think of with these shoes is that they are very much meant for outdoor wear when walking and running. You can wear them indoors, of course, but beware of wet floors. These shoes slip on wet linoleum more than any shoes I've ever owned. I don't deduct a star for this because that's just something I've discovered when wearing these shoes outside of their intended purpose.

A note for people with flat feet: I also have extremely flat feet and was hesitant to purchase these as I've always been told my entire life that I need extreme arch support and even expensive orthotics in order to have some comfort when walking. A doctor even told me about 6 years ago that my condition would worsen with age and there wasn't anything to be done about it. Over the past year I've attempted walking more and exercising the arches of my feet and have had less pain and less overpronation than ever in my life. Still, I expected to encounter flat foot related problems with these shoes. I've experienced the exact opposite. These shoes encourage me to walk and run more evenly which has resulted in much less foot and ankle pain. Your mileage may vary, especially if you've never tried exercising your arches to increase strength.