Fun enough read, great note concerning greed, but beware of some body humor.
Plot
When a man shows up on Berk with a yarn about having found the treasure map to Grimbeard the Ghastly's hoard, the inner-pirates of the Berk Vikings awake and the hunt commences. Hiccup's worries increase as the adventure goes on, especially as his position as heir may be at stake.
Morality
Hiccup is a pretty good kid, though he sometimes has to resort to craftiness in controlling his little dragon with a huge attitude. Even when he's in danger, he cares about the lives of those around him.
Unscrupulous deeds great and small are clearly such.
Spiritual Content
Mentions of Valhalla, Woden, and Thor. A brief episode shows that the Vikings are extremely superstitious and afraid of the supernatural (said "supernatural" event is proven to be otherwise).
Violence
Trips, falls, hits, squeezings, near-slices, dragon-tooth/claw threats. Someone is impaled. A creature's transparency allows one to see its dinner being digested (made up of a few dragons and, at one point, a man in the earliest stages of digestion). An intentionally unsheathed sword nearly kills Hiccup. A fight between good guys and bad guys plays out with a few casualties.
Drug and Alcohol Content
Black currant wine is brought out for a toast.
Sexual Content
None.
Crude or Profane Language or Content
Body humor appears several times. A couple characters are called names.
Conclusion
An interesting read with great things to say concerning greed. While the counts of body humor are less than in How To Train Your Dragon, it's still going on.