In comparison to the movies. The character Toothless is completely different, and isn't a Nightfury at all. Fishlegs is his friend and Astrid is added to the movie. The plot is different also. The Vikings have dragons from the beginning and it is only the means of training that Hiccup on which has an impact.
I would give this book 4 out of 5 stars because of David Tennant's reading. Without it I would probably give it a 3 out of 5. There is some violence between dragons, bullying, and silly names. The age appropriate for this series is 8 to 12 years old.