There's a lot to review here. To start with, there's the original writing by Nietzsche, including four complete works many excerpts from his other works and letters. There's also the translation from German to English, and the curatorial choices of inclusion, both by Kaufmann. This is a great cohesive package. Having started from nothing before reading this volume, I now feel like I have a strong overview of Nietzsche. That's saying a lot for a single volume.
This volume begins with quotes and letters, which like the other selections in the book, are exhaustive, and do an excellent job of revealing both Nietzsche the man as well as Nietzsche the philosopher.
The first and largest of the complete works is Thus Spoke Zarathustra, a ponderous tome using a forced pseudo-biblical writing style. Nietzsche considered this his masterwork, which is revealing both of his obsessively strong attention to detail, and also of his tendency to frustratingly cleave to ideals beyond feasible use. I struggled through much of the book before finally giving up midway through the third part. This is Nietzsche at his most inaccessible and overblown, though there are certainly passages of brilliance. Nietzsche really could have used an editor for this work.
The next complete work was Twilight of the Idols, which is a wonderful distillation of Nietzschean thinking. This is both the easiest book to read, and the best example of Nietzsche as social philosopher. If somebody is looking to start studying Nietzsche, this is the best place.
The last two complete works, The Antichrist and Nietzsche Contra Wagner, are Nietsche's last works before he entered the asylum. It's tempting to see these as the last, strained work of a dying mind. Though I could find a few snatches that supported this view, I think they stuck out more because I was looking for them. Earlier works, such as Zarathustra, seem to show as many or more flaws. There's a bit more strain in these later works, but I think that has more to do with the fact that Nietzsche is overreaching with some of his arguments here.
Though I'm no Nietzsche scholar and thus have no experience with similar Nietzsche overview works, I can recognize that the translation and quote selection are both very strong. There's a good amount of discussion about the difficulties of translation in the editorial preface to Zarathustra, and the excerpted quotes are almost always Nietzsche to the hilt, delivered with his trademark incisive clarity. The editorial commentary by Kaufmann is also very good, identifying Nietsche's strong points and calling out the philosopher when he gets overly disconnected from reality. This collection, published almost 60 years ago now, seems to still be the definitive starting place for Nietzsche, and that's a testament to Kaufmann's work.