I feel like these would be awesome if they used a regular sole that had some type of fabric laminate to it as opposed to using a "flipflop" sole that relies on open air to allow for breath-ability.  Aside from that, very comfortable and lightweight.  Oh and the other knock is that the sole protrudes out about 3/4" on the toes which has lead to me tripping up on sidewalk imperfections.  Must subconsciously modify stride to prevent this trip.