I am 5'7" and 130 pounds and this fit great. The legs go down to my ankles (I was afraid from some of the reviews that it wouldn't reach my feet but it did) and of course it's really baggy in the main body but that was expected since it's one size. I actually chose the "Regular" size because I bought it from a Prime source. It also fit my husband who is 5'11" and 165 and it also fit him well.
My daughter loves this and has had this costume for a few years! I even wash it in the washing machine and dryer! Super soft and comfy!