Like all war books, pinpointing the appropriate age to read this book is difficult.
I read this book at the age of 12 and couldn't put it down, This is a very well written book. For kids who are easily emotionally effected, I would not recommend the book. However later in time I feel it should be revisited. "Code Name Verity" Is practically two books in one, told first by the point of view of the main character Verity herself and then by her friend and pilot for the mission Kittyhawk. This builds a very strong emotional link between the two friends. The smoking is is very timely for the setting but there is no drug use. As far as sex goes, there is none. There is a brief talk of the main character menstruating but it is very brief. The violence is quite relevant to the story line and fairly brutal giving the fact that Verity is being held hostage by Nazis, But I do not feel that it is overdone. The language is there, but not terribly frequent. This book has great role models especially giving the fact that it was rare for women to go into action during world war two. Overall I feel this is a great read and will still interest girls who don't like historical fiction. (I know I don't)
Hope this helps!