EVERY pair of happy socks I've ever bought have developed holes in the heel area. I'd estimate I've bought around 10 pairs.
Edit : My Banana Republic socks hold up better than Happy Socks.
this is my first batch of happy socks, but the initial feel quality seems pretty legit. as far as durability goes, i go through my cashmere socks way faster than the cheaper stuff like those uniqlo blended socks, and that has less to do with quality and more with durability. those nylon, polyester materials, etc. really do extend the life of socks. but treating yourself to nice socks knowing that you'll throw them away soon make for a luxurious treat. the happy socks, however, are less about luxury and more about fun.