The book Norse Mythology by Neil Gaiman is, as the title promises, a retelling of the Norse myths by the author in question.
We begin with Ymir and the creation of the world, we met the gods, including Odin, Thor and Loki and learn their stories. Everything of course ends with Ragnarok, the end of the world and it's rebirth.
In his introduction, Gaiman states "I've tried my best to retell these myths and stories as accurately as I can, and as interestingly as I can." And this is indeed a very faithful re-telling of the stories from the Eddas. Small details are different, but nothing of major importance is changed. The most important change from the Eddas is that Gaiman arranges the stories in some kind of chronological order, so that the book goes from creation to apocalypse. But Gaiman doesn't try to impose some overarching plot of his own. He doesn't even try to resolve the small contradictions that exist between the different myths..
Of course the myths are such powerful stories already that they don't need changing. And Gaiman tells them well. This is simply a well-written book. Gaiman knows how to make effective use of the inherent dramatic and comedic qualities of these stories.
However, his faithfulness to the Eddas make this book somewhat redundant. If you have read the Eddas, there is really no need for you to read Gaiman's version of the same stories. The Eddas can in translation be perfectly enjoyable reading despite their age. And if you want a more accessible re-telling, there are many other faithful literary adaptations which serve the same function as Gaiman's book.
Of course, there are always people who are new to Norse mythology and in Gaiman's book they will find an accessible and well-written introduction to the stories. And for those who already know these stories, this is a fine, albeit non-essential way of re-experiencing these evergreen stories
