I think it doesn't make much sense to compare Neuesachlichkeit to Fight Your Own War. They have very different approach and purpose. Originally, when SI started, the hopes where the 80's/90's style "anything goes". Not specific sound, not specific labels, not focusing on one corner of the genre. Book like FYOW probably aimed to do it in a bit same way, attempting to cover slightly wider range of approach. I would assume it would be vastly better, if it was like vol 1, and to be expected more. Handful of volumes that give attention to even more countries, bands, subgenres, different aesthetics and so on.
In such case, it wouldn't matter much, if one particular volume is not perfect document of history, but ongoing documentation, hoping eventually to build wholeness that has purpose. As example, I am not overly concerned if all issues of SI are equally good and equally interesting, or gradually getting better. I'm more interested in situation, how I would feel of the pile of stuff when issue 20 comes out.
Neuesachlichkeit is very focused zine/book, and there is certainly audience for this approach, myself included. It is also easy to conclude that claiming it to be "vastly better" compared to something else, is easily dismissed if reader is into even slightly different part of scene? If sex & violence and all things extreme is not your liking, there is very little Neuesachlichkeit would offer?
I personally recommend to get all, though. This book, Neuesachlichkeit, Personal Best, New Forces, and so on. Each have enough content that can be skipped and continue from next piece.