I'm used to Vibram Five fingers 3mm so these were a little thick on the bottom for my tastes. But they still feel better than regular sneakers.

(edit 6/20/2013)

I wore these on my vacation to Rome and I found out that they were def. the wrong size for me. There are 2E I think I'm a 4E or whatever the widest size is in sneakers. After the first day of walking all day, I had blisters and sores all around my feet. It would be nice if they sold a wider size.