My daughter insisted on being Supergirl for this Halloween, and I really like the costume.  She's very petite for her age (3 1/2) and this costume fits snugly with only a long-sleeve tee shirt under it, but the skirt comes to her knees and the boot (shoe covers) come up to her knees.  I put some warm tights under it and hopefully she'll be fine for Halloween, and it moves comfortably with her.  I'm very satisfied.