Interesting read, but I would not recommend it for children.
This book follows the story of Turin, son of Hurin, after Hurin is captured by the evil Morgoth and is placed under a curse, along with his family.
Turin often has problems with his pride, something that gets him into many, many trials. He also makes many bad choices that get him into trouble.
Hurin was cursed by Morgoth - who in The Silmarillion is clearly shown as a fallen angel - for defying him. The Valar, who are angel-like or god-like spirits that protect the earth, and the Maia are mentioned - specifically Melian and Morgoth. A comment is made about the possibility of a character having escaped "from the pits of Hell".
Early on in the book there is a battle called "Battle of Unnumbered Tears"; and many central characters die, sometimes in horrible ways.
Drug and Alcohol Content
There are some references to both the men and elves drinking, but only in passing.
There is a case of incest that becomes a key plot point - a brother and sister who have never met before marry without the knowledge of being related - but this is strictly condemned and it has a tragic end.
Crude or Profane Language or Content
There are some cases of people being unclothed, but it is not graphically described, and not in a sexual way.
A very depressing read, though interesting. I would not recommend it for children because of the violence and (condemned) immorality. I would highly recommend having some knowledge of Tolkien's Middle Earth before reading.