We could think that the episode is bad, but it isn't. Althoug the strory was kinda familiar (The importance of being Phoebe) theres was the same!
I think that the episode is so original (Leo being possesed,Piper "opening" the door of the doll house, Piper and Leo running next to the doll house...)
I think that the Book scene so great (When they are in the top next to the book, and Piper blows up in the book to move the page) It is vey original!!. The effects are fine, the shadow idea is great too(At last we saw what happened if you control the shadow)
I don't see the reason why this episode should'nt be awesome! THe only boring think is the Phoebe and Paige scenes in the work! but there're acceptable!