Fabulous!  I purchased for my 5 turning 6 year old in size 5-6 and it fit as expected with a small bit of room for growth.  My daughter absolutely loves it and it is easy enough for her to donn fully on her own which is a huge plus as it's intended for dress up/costume play.  My only complaint is that the buckle straps are pretty pointless.  They do not attach to the white jumpsuit itself and have no points of adjustability.  AS such, the straps just slide straight down on the waist portion and off the shoulders.  Other similar costumes also for sale on amazon, have belt-loops, where the straps fit through for anchoring.  This particular costume does not have any, so you either have to sew on your own, or just ditch the straps altogether.