I got 2 pairs of these for people as Christmas gifts and then decided to buy myself a pair, too.  As far as I can tell, they are true to size.  I got a size large for both recipients, who wear a men's size 10 or so.  The colors and patterns are really fun and bright and people seemed pleased with them.  They are thick, have a little bit of stretch, but are cotton so they breathe well.  I also think it's really nice that they are made from recycled yarns.