This costume is great for toddlers.  I'd put the size at about a 2T.  It's well made for a costume.

This is a mini dress and it doesn't have a bodysuit and underwear/diapers are visible if the child bends over or runs around in it.  You may need to get some bottoms to complete it.  The stitching is well done and firm.  The costume washes well.  I put it on delicate wash and hung it to dry.  After it was dry, I put it in the dryer on a refresh cycle for about 10 minutes to remove wrinkles.  (There weren't many.)  Most messes wipe easily off of it.

I'm not a big fan of the legging/shoe covers as they tended to slide down and weren't as consistent with the sizing of the dress, but were perhaps made for a slightly bigger child than the dress was. There is no bottom to them, but just an elastic strip to hold them in place under the child's shoe.

The arm bands slip on and the headband has an elastic band around it to hold it in place.  My concern with that is that my daughter pulls it down around her neck to wear as a necklace and I worry about choking if it gets caught.  The belt is sewn on and doesn't come off or move around. The cape attaches to the dress with velcro.  It stays on fairly well even when the child is running around.

All in all, it's very cute and well-made.  I'd definitely recommend it!