The dress is very cute. Great for little girls who like to wear dresses.
My daughter is 4 yrs old, 38" tall, 31 pounds. We purchased the 3T-4T size. Fits great (w/room to add an undershirt for warmth).
The only suggestion I would offer is this.  The head piece is cheap, flimsy and ours arrived wrinkled.  So, I went to Craigslist and bought a real wedding veil for $5.  This wedding veil was a $75 veil & what a deal for $5, my daughter will wear it with this costume and together, the ensemble looks fabulous!  Also bought the white disney gloves (those are a little big) that go up to the elbow to tie it all together (and for added warmth).