I Don't read a lot of children's books but, being a Lord of the rings fanatic and the movie coming out, I thought I have to read this book. 
 I do believe that it is indeed a children's book, it feels like a children's book but it doesn't feel like the writer was talking down to children. I did love how the fantasy elements provided such creativity into this world and allow children to explore that. The villain is basic, a dragon who stole the dwarves gold that they want it back, but the thing is, it's a children's book after all 
 Ending was sorta sad though, after the battle 
 As someone who loves Lord of the rings, I did love looking into Bilbo's character and read about his character prior finding the ring and after that before thinking about the changes he went through up until the Lord of the Rings books started