Watch out, these shoes are not sized correctly. I ordered a US 10 which should be a Euro 41, but the label said 10 / 40 (a 40 is a size 9). They are mislabeled. I can't imagine it was just my shoes that were mislabeled. I an going to return them since I would have to pay to ship them back if I were to exchange them.
But, if they did fit I think they would be comfortable. Probably not breathable, since the materials are manmade, but very cushioned.