It's complicated sums up the novel perfectly for me. I'm really struggling with forming my opinion on it, so there might be a future update. 
Currently: I get the themes of love, war and friendship. They are communicated through the lens of a 17 year old boy. He is a bit dry and unsure of life but maybe that's just teenagers. For me, he felt too distant. The writing was straightforward and uninspiring. 
Especially the ending makes this book so hard to rate. You just wonder: why? But maybe this is the point of life and character driven stories? Wow, really philosophic haha! 
The thing I enjoyed reading about were Franz' relationship to his mother, his "boss" Otto, Sigmund Freud and Anezka. That really makes the book and shapes the main character. 
Should you read it? If you're into coming of age stories during a world war 2 setting in Vienna with a boy in puberty... go for it..