I had to read this in primary school, and have re-read it many times since. It is a classic tragedy with sad but complete ending. If you enjoy The Hobbit but also enjoy real history, the this book (based on a true legend and person - in best Hollywood speak) will take you away to the times of true kingdoms, honor and mystery. If you've ever wondered about the provinces of Ireland and the quarrels arising from them, if you've ever driven the Antrim coast and read the titles of kings that died in the ruins of Dunluce Castle, if you're tired of saccharinised tales of CGI vampire love, and want to have a feel for the character of the past, then read this. Suitable from 9 to 90.
Now I know the myth and legend of a true Hero of Ulster. I love this fantastic warrior character. Stuff Thor and the Norsemen they should make films about the exploits of Cuchulain (The Hound of Ulster)