I normally wear an 8, however I really should have read other Muck Boot reviews and got a seven. Had to return my first pair and order a 7, which does fit pretty well.
A plus side to these boots, they fit my rather large calves, which is nice, although I can't say the same for the rest of the Muck Boot line. (DO NOT BELIEVE THEM when they say the material they use will stretch to fit "virtually any calf size.")
Anyway, the quality of these is pretty good; the tread is awesome. I haven't had the chance to wear them when it's raining, but so far they've done great when I've been working outside.