I very much enjoyed If I Stay, which is the book that comes before Where She Went. In If I Stay, we are solely focused on Mia and what happens to her after the car accident. In Where She Went, we get to see a lot more from Adam, which gives an entirely new perspective. 
 Where She Went was more emotional for me than If I Stay, even though it seems less serious than wondering how Mia will fair after her accident. Adam and Mia find each other, years later, and both struggle to explain their feelings - making Where She Went an entirely different book than If I Stay. 
 That being said, I really loved Where She Went, even more than If I Stay. The complex emotional thoughts of Adam and Mia in Where She Went gave the book a gritty, real feel that isn't easily accomplished. 
 Emotionally driven, Where She Went tells a better overall story of Adam and Mia, and Gayle Forman does an excellent job of displaying grief, love, heartbreak, and the past. Her writing will take you through a range of feelings, and many will not want to stop reading once they start.