The Scions of Shannara is the first book of The Heritage of Shannara.
In my opinion The Scions of Shannara is one of the weakest Shannara books. When you read it, it's easy to see that it's clearly the first part of The Heritage saga.
This book is readable, but the other books in this series are much better.
By the way, if you're familiar with the translations (the Finnish translations) and have read them, you should read The Sword of Shannara Trilogy before you begin to read this series. It's good to know what has happened earlier or you won't enjoy this series.