I ordered this costume on a Wednesday and was happy when it arrived Friday. It is really well made for a costume but the velvet body fabric is a bit thin and mine came apart at the seams a bit when I tried pulling it down so the skirt would not be so short. No problem sewing it though as it was near the seams. I am 5'7 and I am a size 4. I considered buying a S but I bought the XS because so many reviews said it runs big. I wish I had ordered the S. It's not too tight but it is a bit too short through the body. This makes the skirt come just 2" past my butt. I considered sending it back for the S, but the belt is already too big (very easy to fix, I just took off the velcro & sewed it back on where I needed it) and the front of the skirt looked about as long as it does on the model. I am assuming that the body of the costume runs short. I think a S would be better for me but not so much so that I'd return it. If you are 5'5 & under, I imagine this costume would be perfect for you. If you are taller than 5'7, just be sure not to order a size down. Order your size and it might cover your butt. I'm going to wear cheerleader spankies under mine. I think every girl should have a pair for Halloween because cute costumes are always so short. And by the way...the boot tops are completely useless. Be prepared to order some red boots (I've ordered the same ones others are mentioning here) because you really do need boots with a supergirl costume.
*Edit: a few unhelpful comment ratings lead me to believe that perhaps the cut is not consistent for this product. Or maybe if you have a particularly short or long waist, that should be something you take into consideration also. Despite these things, I still think it is great quality for a Halloween costume!