Terry Brooks is best known for his Shannara books which tell fantasy tales about life after a cataclysm. His first books occurred quite a long time after the so-called Great War and were fairly standard adventure fantasy books modeled after Lord of the Rings. He then started three series about events which led up to the Great War. This book is the first of the third series. The Races are learning that the protection around their valley is failing.
It's too hard to describe the story further without spoilers, but suffice it to say this book has the same elements of magic as in the other Shannara books, but with a more interesting plot. It feels much less linear than the chronologically-later ones and feels like a further departure from the Tolkien style. Fantasy books are now much grittier (see Abercrombie, Lynch, Martin and Rothfuss) and it's a welcome change from the elves and dwarves stories.
I'm also more a fan of post-apocalyptic stories than post-post-apocalyptic ones. I like stories about what happens right after the big event - how do people cope with the ensuing anarchy? Who steps up?
Anyhow, I recommend this series for those who like the genre.