I have been using these socks for the last month for winter kayaking. Getting in and out of my kayak I step in the nice cold river water. These socks keep my feet totally dry and are much more comfortable than the gortex socks or rubber socks that I've had in the past.  They also offer insulation and allow me to wear fleece socks underneath for added insulation. I've had 2 other friends buy these socks and we all LOVE them.
Note: The top of the sock is not sealed so if you step in too deep of water, it can get in from the top. Seal Skinz do make socks that have a seal at the top although I don't know how good they work.