The fit is perfect!  I'm 5 feet tall, 140 pounds and I ordered size large.  (PJs always shrink up a bit after washing.)
The size large on me is perfect.  I know that I could wear a medium, but they would be more fitted and less comfortable.
(Depends on your priority I guess.)
They are long on me ... but that is fine, I just roll them up. - I think that they would be comfortably long enough for someone as tall as 5'6" or 5'8".
The quality is excellent.
They are thick, they are soft .... and THEY HAVE POCKETS!!!
: -)
I have just ordered another pair in a different color ... I'm considering ordering a 3rd an getting rid of my old PJs all together.
I'm 50 years old and they are the most comfortable PJ bottoms that I have ever owned!
I would definitely recommend .... "10 times over!!!"