The one thing that really bothered me is how the author switches from one person narrating to another and it's not always clear when this happens so it sometimes took me a couple pages to figure out who was talking. This can be a very effective tool in telling different viewpoints of the same story but not so much in this case. For one thing all the narrators talked exactly the same. If you're going to have another person telling the story from their viewpoint they should have their own individual style of talking. Even though the story is being told by a different person it's being said in the same voice so it's not believable. 
 I like reading stories in the first person but if you're going to use that style then you need to make the switch in your head so each person has their own distinct voice. I don't understand why this wasn't more easily taken care of since the book is actually written by 2 people which makes me think 1 person comes up with the ideas and perhaps the plot while the other person actually does the writing.