We bought this for our just turned 2 year old at Christmas and she absolutely adores it. Out of the 4 books she has this is by far her favourite. She even takes it to bed with her at night and 'reads' it with her nightlight!
The questions the princesses ask are in the same order every time you play which means that very quickly she learned to get the right answer. I am guessing that the repetitiveness of it which is so ideal now, may in fact be its downfall later on and I certainly don't think there is enough in it to keep her going until she's 4 (hence only 4 stars) but for now it is just perfect.