My second favorite book in the series. 
 (view spoiler)[ 
 I love how Elizabeth's personality change gets Jessica back in a way for the awful way in which she normally treats her. (hide spoiler)] 
 Reading these books again as an adult, I get frustrated with the twins quite a bit: Jessica for being a horribly selfish person, and Elizabeth for enabling Jessica's bad behavior. It did help to read that Francine Pascal envisioned the twins as portraying the good and bad sides of human nature. Given this, the hyperbolic nature of their responses to things is more understandable, and this makes me less frustrated and able to enjoy the series more.