IMHO, the problem isn't that Ekerwald doesn't know enough about his subject, it's that he can't adapt his style of writing to to writing a biography that's reader-friendly. Instead, he puts way too many interpretations and supposedly clever turns of phrase into his text in a manner that makes this more of a (very much) overlong article for the (somewhat snooty) culture pages of a newspaper. When you write a biography, you should (IMO) concentrate your stylistic skills on getting the facts about the person's life and work readable and understandable the reader, not pushing your own opinions or stylistic quirks onto said reader. Ekerwald doesn't really succeed in creating a compelling, coherent narrative about Nietzsche's life and thoughts that holds together because he constantly interrupts it with small excursions of his own opinions and comments.
So is this a waste of time? Well, no. You do learn quite a bit about Nietzsche, only not as smoothly told as I'd like. Me, I basically a) pity Nietzsche for the painful life he had to endure, both in terms of illnesses and personal (and interpersonal) failures and disappointments; and b) don't think he's entirely blameless for becoming the "Nazi philosopher" even though he wasn't a Nazi philosopher and was more or less co-opted into the movement by his sister skewing his work in that direction after his death.
Why not entirely blameless? Well, I think – and this is an opinion that has evolved while I've been reading and thinking about Nietzsche – that anybody putting forth an opinion, world-view or somesuch has a responsibility for what they're saying. If what they're saying is hateful, racist, anti-democratic etc, well, obviously they're responsible for their hateful opinions and writings. If they're not really writing hateful stuff, but formulating it so obscurely that it can well be interpreted that way, they're responsible for that as well – obviously far less culpable than in the former case, but still responsible for their texts. If confronted with that interpretation of their text and responding "no, that's definitely not what I meant", then that's that, and you can't smear them with that interpretation, but you can still express your wish that they'd written their text more clearly.
(Unless of course you're some abject idiot projecting his or her own fear and anger onto the text to make it out to be something hateful; heaven knows there's plenty of that going around in this polarized political environment.)
Anyway, there are many who write philosophical or political texts that are unnecessarily obscure; whether because they're just not very good at writing or because they think it makes their texts "better" probably varies. The result, however, is the same: the text is left open to interpretation, and different readers can project their own opinions onto it. (As can various critics, literary and political journalists etc, making for great debate fodder – debates that are basically a waste of time that could have been avoided had the author bothered to write more clearly to begin with.)
(Note: I'm trying to be clear with my opinions on this blog, so if I'm being unclear, it's due to bad thinking and/or bad English and writing skills. Just so's you know.)
But to get back to Nietzsche: He loses his father at an early age, grows up a serious little kid, comes to excel at school (except for math) and university, becomes an up-and-coming philologist, a very young professor, befriends Wagner and has a brilliant career ahead of him. But he becomes bored with the details-oriented academic work and becomes a more speculative philosopher instead – when he's not incapacitated by migraines and violent indigestion, of course. Eventually basically retiring from academia due to his health issues and living off a pension, his philosophy meets with limited success. I won't try to describe it here, as I don't consider myself competent enough – and because it's so unsystematic and goes off in so many directions that it would take a lot more time and space than this simple blog post can offer. Instead, I recommend this Wikipedia article as a good starting point or summary.
So, I can't really recommend this book. And I can't really recommend Nietzsche's philosophy, either – as with so many other historical philosophers, if you want to learn more about the subject(s) they're speculating about, read what modern research on the issues says instead. It won't leave you quite as erudite as studying the philosophers would, but it's a heck of a lot more efficient if you mainly want to learn how the world actually works.
