I have ordered these in a few colors and have gone through a few pairs.  They are amazingly comfortable.  I do put a small shoe liner inside for extra bounce in the soles, but generally, these boots fit like a slipper.  The suede style is always true to size, however, I ordered the leather style for the first time and it seemed to run a size larger. I chose to keep them and wear them with thick socks and put one of those very thick gel sole inserts inside.
I still love the suede version the best.  These boots do not last very long, however, and they are not water proof, but they are still my favorite.  For the reasonable price, I just buy a new pair when the old one wears out.