This costume definitely runs small - be sure you size up at least one size bigger than you'd normally buy, and consider 2 sizes up. The back has a tie so you can always adjust it smaller.  Also it is quite short, which I don't think is clearly visible from the photo of the product on the webpage. Plan to have your child wear black pants to minimize that issue.

I do like that the costume is one pull-on piece. However, I'm not at all sure that it is going to survive 2 parties and Halloween night. It seems fairly flimsy in construction.