I am wearing these now and have worn them a couple of times.  I normally wear a size 5.5 in women, 4.5 in boys.  This one fits but there is still quite a bit of room.. considering this is for 5.5/6 I understand.  I don't think even a thick pair of socks would change it much..
Still testing the waterproofing but so far my feet stay dry... they get colder than my old boots but for the price these were really good.  We'll see how long they hold up
2/8/13 - UPDATE:  So I've been wearing these a month and the insides are worn out quite a bit but it doesn't effect the waterproofing (yet).  I'm also noticing a few 'cracks' forming on the outside (where the toes meet the foot and bend).  So far I'm still dry but hoping these at least last 1 season of winter.  Keep in mind I do wear them everyday now and walk quite a bit.
6/25/14 - UPDATE: These have been retired from my shoe collection after this past winter (so definitely earlier than June).  I had to buy inserts because my feet slipped a good bit.. the fabric started to bunch together so it felt like I had something in my shoe and gave me a few callouses.  The waterproofing definitely didn't last once the cracks started to form (and you could see the white fabric peek through).  That said, the insert kept them through the rest of the season but I'm off to buy new winter boots and I won't be picking these again.