For the most part, I liked Wonder. I thought Palacio did a great job of making Auggie seem like a very normal, average boy with the exception of his physical different-ness. His voice feels very authentic, and I love that he loves Star Wars. I also liked the chapters told from his sister Via's point of view, but I thought the other POVs pulled the focus off of Auggie (I am reading this book for his story, after all!)
The book lost me is at the very end, where the conclusion was overly sentimental, basically undoing all the good will it had been building over the course of the story. I can't say too much without giving away what happens, but I will say that I was disappointed in it.