This is by far the best Sauron apologetic that I have read. While there is not an exact mapping, the characters and events in the book are clearly modeled after the The Hobbit and The LoTR, with just a bit of Covenant and other fantasy mixed in. However, the focus of the story has shifted completely, so that the reader is in the boots of the Orcs/Banelords/Dusky Easterners, and facing the threat of renewed Gondorian/Elven aggression.
Despite drawing so directly on Tolkien, this is still very much its own story. It presents a fantasy world closer to the Israeli/Palestinian conflict, where both sides have grievances that go back to the First Age of Man. And the Mordor side is never a caricature; the author does a good job of portraying their affections, values, and viewpoint in such a way that you root for them at least as much as opposing side. The various events and set-pieces have also been moved around, so that while you might know the events that will happen, you are not sure of when they will happen, or who will fill which role. For example, mid-way through the book I was terribly anxious that the Gandalf-analog would carry out a Helm's Deep type charge from behind, ruining the plans of our heroes and their orcish army. Something else happened, but still, half the fun of the book is re-arranging the various puzzle pieces of known events and trying to guess how they will be arranged into the story.
Another selling point to the book is that it is much more straight forward than the original. Characters are clear and distinctive, and events move at a fast pace. Rather than rambling on about elven poetry, this book dives straight into the strategic/magical balance of power. Altogether delightful, assuming you are into this sort of thing.