I am 5'6" and roughly 125 pounds, and the small fits me really well.  It's really nice looking, and I've had several compliments.

The belt could be tighter - it doesn't look loose or anything, but it doesn't create a cinched look on me.  I look somewhat tube-like.  I don't have the sewing skills necessary (nor the desire) to fix it myself.

I wasn't sure how it would hold up to really cold temperatures considering it's lack of bulk, but I've been wearing it outside in 20-40 degree weather recently and stayed toasty warm.  The length of the coat is really nice for this reason - the tops of my legs stayed warm too.

I've had it for about 3 weeks now, and today a feather poked through the fabric, which was not all that surprising I guess - all feather-based coats I've had have this problem.  I pulled it out and another feather tip took it's place.  I don't want to just keep pulling out the feathers, so I left the tip there.  It didn't make a noticeable hole in the fabric yet, but I don't want to make it worse by continuing to pull the feathers out.  And now a snowy white bit of feather can be seen.

The hood is interesting.  I've only used it a couple of times, but when I did use it, it hangs down pretty far - actually a bit over my eyes, which was irritating.  I was able to "reshape" the hang manually to keep it out of my face, but it's natural inclination seems to be to hang down to my nose.