I purchased this product for my daughter and was very disappointed in the build quality.
One of the arch pieces wasn't even fully formed properly and wasn't usable. (try explaining that to a child on Christmas Day) Generally the pieces felt cheap and don't click together properly. Unlike real Lego, they fall apart easily and don't align properly. After building a couple of levels, we found the pieces didn't lineup at all, which made it hard for a child to place/fix the next bit. Once built the model fell apart. The colours also look cheap and de-saturated. They don't have the same depth of colour as real Lego.
Generally the product was disappointing and didn't have the same playability as true Lego. We're now trying to avoid this set getting mixed with our existing Lego, incase it affects future builds.
Whilst this castle looks ideal for girls, I'd suggest a getting a genuine Lego set and making your own Princess Castle, perhaps using a Harry Potter set or something. It may cost more but your child will get many more hours of fun from this and you'll be left with a quality toy for generations.