I normally fit a 10.5, so I went with the size 11 G4 (it's annoying that there aren't half sizes, btw), and the fit does not feel secure enough for barefoot wear (you mean I need a sock inside my barely-more-than-a-sock 'shoe' thingy?), as they fit slightly loose, letting the foot slide around inside. Ruling out any possibility of a better fit with the next size down: the rubber sole cups around the foot and tends to press in on my little toe, which is very irritating, if not a tragic design flaw considering that a proper barefoot-like feel requires allowance for toe splay.<br /><br />As for materials? The smothering neoprene/TPU construction makes the feet grow sweaty quickly (which only worsens the issue of slipping). And then there's the fact that the sole is held to the upper with glue... and upon receiving them I immediately noticed it was either peeling away already or had simply not been properly glued on in a couple spots. Either way, it reflects poorly on craftsmanship.<br /><br />On top of all that, the specific shape of the sole, and how it connects to the upper, causes a hideous buckling to occur right around the center of the interior side of the foot. And it's not just on my foot; I see this in every photo. This causes what might otherwise appear to be a simple sock to take on the appearance of a sock worn through mud, taken off and allowed to dry, then put back on once the mud had dried and deformed.<br /><br />Despite the issues, I briefly considered keeping them for winter house slippers. But they're simply nowhere near being worth the money, so I returned them for a refund.<br /><br />For now I will be sticking with Vibram FiveFingers for all athletic needs despite the small issue of having to individually align the toes when putting them on. I may try the Soft Star Moc3 next.