I normally wear a size 7 shoe and have high arches and wide feet.  Based on the other reviews, I ordered a 7.5 which is perfect with boot socks.  There are very handy loops on the front and back to assist with pulling them on.  I've been out in the snow playing with the dog for up to an hour and my feet stayed warm and dry.  The reason they got 4 stars and not 5 is the zippers.  They tend to stick at the same place more often than not.  They (the zippers) appear to have been treated with something to help keep them water-tight and I hope that after a bit more wear and breaking in they'll improve (I've only had them a week).  The box said that they are machine washable.  I haven't done that yet so I can't speak to the results but I was pleased that it's an option.  I have a pair of Keen slippers that I've washed several times with excellent results so I don't expect this will be any different.