We bought this for our daughter's 5th birthday along with Princess Liana's partner doll, Alexa. Why 2? simply that the price had almost halved and they sing in tandem so thought we would get both.
The build quality is the usual Barbie doll quality and will withstand medium play. The shoes are awful and do not stay on, the tiara is flimsy, but otherwise pretty good. We have resorted to using blue tack in the shoes to keep them on and much better now!
The famous transforming dress: at the back of the doll is a plastic pink "clockwork" type key. You turn the key and the left and right front panels of her dress lift up and swoosh round to reveal the glittey lining panels, creating a new outfit. It is fairly successful, certainly my 5 yr old thinks it is "incredible" but I wonder about how well the mechanism will last. The dress is very stiff with plastic bits in the hem of the panel which does help to keep the panels stiff and hold their shape well. We had to realign part of our doll's dress with a few careful tugs and bending as the doll kept flashing her knickers (to the amusement of her elder sister and the upset of the doll's owner!) The downside to this is that it makes the doll feel very awkward and a little stiff when a child holds her - especially with the bulky key sticking out of her back! Not the end of the world, but not the same as the regular Barbie dolls when a child is playing. The turning of the key also switches off the music if wished - nice to be able to cut the song short if the phone rings or trying to get the dolls to sing in sync and keep wanting to restart.
The music: same quality of sound as previous Barbies, it is ok. You can hear the words to sing along and the volume is pretty loud. As an adult I would expect a little better sound quality for the price of the toy, but my daughters seem not to notice or care about that side of it! The doll sings two songs from the movie. The singing is activated by a button on her hand. She alternates the two songs. While the doll singing solo is ok, really it is designed as a duet to sing in tandem with her partner doll, Alexa. Liana's part does sound better as a solo doll than Alexa so if you are only intending to purchase one doll, I suggest considering this one over her purple friend. The idea of the button in the hands is that if you press their hands together they will sing together. Only partly successful, we often found one would start singing and have to start all over. It is suprisingly tricky to sync them exactly and my daughter resorts to lying them flat on the floor and taking a deep breath, pressing one with each hand! Not quite the simple "hold hands and sing" method as suggested by the advert!
So, all in all, I still think the doll is expensive at current prices but no doubt the price will drop further before Christmas. It is a pretty doll and will appeal to all Barbie doll loving children. Out of the two Princesses from the Parbie Diamond Castle, this one is better as a stand alone singing doll as the music does sound more convincing than Alexa. The dress is a bit gimmicky but kids will love it anyway.