Books that deal with theoretical endgame positions, there are a dime a dozen. (Foremost Dvoreckijs Endspieluni and also the Müller / Platen.) Books about endgame strategy (like this), however, are very rare. And good even rarer.
To the classics of Schereschewski and the recent work of Müller / Pajeken is now joining this new book of Hellsten.
And it must not hide behind the above. On The Contrary!
For me it is exactly the book about endgame strategy, what I've been looking for.
All relevant strategic topics. The book is structured meaningful and the many examples are wide-ranging and chosen instructive. Verbal statements and variants have a balance. Also helpful are the cross-references between the examples in the book.
The book is a real treasure trove and it makes me really fun to work with. :-)
However, it is not a book for beginners. The knowledge of basic theoretical endgame positions should already be present. If you have that, it is my opinion but considerably more sense to first make this book, rather than yet another exotic theory einzubleuen positions. The benefits will be much greater.
Highly recommended. ;-)