Given the original poster was looking to upgrade from Castelli, I think he was looking for something a bit more aesthetic than duct tape.

Having said that, while I try to retain some weak semblance of style throughout the winter, I am willing to try pretty much anything in a pinch rather than have my toes fall off. Plastic subway bags make pretty good oversocks when needed.

Back to the question, it seems that arbitrarily some overboots (booties) are waterproof neoprene and some are not. My garneaus from a few years back were pretty warm below freezing, but the first time it rained I found out that water just soaked through them. The MEC booties I had were thinner and not as warm, but are totally waterproof. Anyone else have insight on what's waterproof and what's not?