@aidan,
I only had problems with these shoes when I tried to run in the rain. The friction between the wet feet and the material of the shoe gave me a couple of blisters.
Other than that, I've never had any problems with them (but it's only been 3 weeks). I don't have a problem with many pairs of shoes though, so I might not be a good gauge.
It's important to know that these shoes do not provide any support though. They pretty much mirror the shape of your foot, and if your foot bends/arches/etc the shoe does the same. There is zero support with these guys.
The rubber on the bottom is thin enough that you will feel even the smallest pebble, and change in terrain, but you can step on glass and not get cut. It's probably 1/8th to less than 1/4in thick.