Our feelings on this book are the same! I also got a fanfic vibe from it, in that it was fun and did relationship stuff and felt good to read, and I also was disappointed by the ending, despite it doing what I wanted it to do. There just wasn't enough care or detail (or feeling!) put into the resolution.

Also, while describing this book to someone, I did compare it to Harry Potter, but only to say that it's the opposite in many ways, as this is a book about a kid who doesn't want to do war...and doesn't.