I felt Pandemonium was a huge step up from Delirium. Oliver can write very beautiful prose, there is no denying that, however prose on its own is not enough to make a book shine. 
 Things I Loved About This Book: 
 - The writing. Like I said above, Oliver can definitely write. Her writing is not perfect (at least, in my opinion) however, I did find myself sometimes rolling my eyes at her cop-out uses of "Suddenly I realized..." and "All of a sudden I felt..." phrases. They were annoying, but I don't think it took away from the story. 
 - The character of Raven. I feel Raven is the only character that Oliver felt like exploring a little deeper. Obviously she plays a critical role in the story, but I feel the same could have also been done for Tack, Hunter, or Sarah. Yet we only get glimpses of them. With the exception of Julian characters weren't really fleshed out everyone is kind of in the background playing minimal roles. 
 - Having the chapters being divided into Then and Now. I really loved how the chapters were broken up and I felt it added a bit of mystery and suspense. 
 - Fast-paced plot and an interesting twist at the end. Oliver doesn't really wait to roll out the plot in this book. It's there from the beginning and it remained fast-paced until the end. 
 Things I Didn't Like About This Book 
 - The love story. I did not get it at all. I felt it was forced and juvenile and I could not believe how Julian would just drop everything and convert to the resistance in only a matter of days. A friendship would have been more believable in my opinion. 
 - The whole deliria world. I just have trouble believing the deliria illness and the whole controversy. I think government removing all emotion from its citizens to keep everything "clean and purified" makes a lot more sense than just eradicating the ability to love. Not being able to love doesn't mean that you won't have to deal with all other difficult emotions that drive people to do harmful things, ie: jealousy, selfishness, anger, greed, shame, etc. 
 That's really about the only issues I had with the book, which is nice. 
 Overall it wasn't a life changing read or anything, but it was an interesting story with an intriguing plot that provided some good light reading.