I doubt the cost-benefit ratio.

So the set includes a doll with Rapunzel's length unicorn shaded hair, a small brush and a similar to hair straightener gadget that has a built in a small heating area that is safe to touch. When the not-yellow hair being placed between the gadget's plates, it changes its shade - brighter or darker, depends on the chosen mode.
The plates are getting warm only when the two gadget's plates manually pressed together. Three AA batteries are not included.

The doll has two types of hair. The yellow colored hair does not change its color (though permanent sharpie would fix it).
The other part of the hair: pink, blue, purple, orange and red, is altering its shades, so your little fashionista could style the doll with highlights, lowlights, splashlights, ombre, sombre, balayage, you name it...
To see the difference the hair should be brightened first and then color-darkened.

I'm not sure for how long that "back and forth coloring process" will hold kid's attention for its fairly limited options play. As just a doll with long hair, the toy is lovable and pretty.
The last thing I want to say a word about is the set's price. In my reviews I choose to omit the subject of the products' prices, but in this case, the cost-benefit ratio is not well balanced.