Technically, this is very well done from the exposure through the processing and the lighting is spot-on. Very well done.
Your model may be a bit young to "be" Rapunzel, but I'd say she's perfect as a little girl playing out the role in "pretend". The biggest issue is her expression. "Rapunzel" doesn't look too happy to be rescued. I know from experience that getting 4 year olds to pose is a challenge, but, unfortunately, this one doesn't quite make it.
The only other thing I can think of is that the background is a nice combination of spring-like colors, but Rapunzel was imprisoned in a tall castle tower. It's really a minor, but noticeable disconnect.
She's pouting! But then I guess when one is locked in a tower there's not much else to do. Dreamy processing works well and having the end of her hair out of the frame lets me imagine it really is insanely long.