Having read this novel, I think calling it an erotic novel is to do it a dis-service (!). It's not exactly "I gazed into his sapphire blue bedroom eyes" or a Harlequin Historical we're talking about. Instead, go for wildly depraved and genuinely messed up collection of high-up Nazi characters as described by Eva Braun.
There is sex in there, oh yes, but to call it erotica ... no thank you. The first adjective that came to mind wasn't "erotic", it was "squicky", because it was about a bunch people getting incredibly frisky very near the end of the war (desperate times, desperate measures?) and not caring who saw them.
The one who gets around the most is Magda Goebbels, the wife of the propaganda minister, who doesn't seem to know how to keep her legs closed. It makes me wonder how the author can get away with writing real people in this way if there isn't any hard evidence that they really were like that in reality. Then again, it's pretty difficult to make someone who murdered her six children in their sleep before committing suicide sound like a worse person than she actually was. And that's even if you put aside the fact that she was a prominent Nazi and married to Hitler's propaganda minister. If anyone has defamed her character, surely she did that job herself!
But it makes you wonder. It says the book has been researched and everything, but I'm left wondering what "facts" are actual, verifiable, historical facts and what's been made up for dramatic purposes.
At any rate, "The Patient Ecstasy of Fraulein Braun" is not "Führer Porn", nor does it paint the Führerbunker's inhabitants and the Nazi party leadership in ways that are remotely flattering, even if Eva herself of course thinks her darling "Adi" is a genius and the bestest thing since sliced bread and she can't wait to wed and bed him, despite him having a variety of not-so-savoury health issues. The autobiography and diary of Eva Braun is not for those of a weak stomach!
You keep forgetting it's written by an American author and not Eva Braun herself, and the only real criticism I have (aside from "OMG, ewwww!!") is the gratuitous use of German phrases. Either stick with the English translation - considering the rest of the book is in English anyway - or don't write it twice it if it's just one word. Or put the translation in a footnote to avoid repeating yourself by writing something like "Verdammt. Damned." It clogs up the flow.
Aside from that, it was an interesting read. I can't say it was enjoyable, because if anything, it was deeply uncomfortable, but it was ... different. Fascinating, in a "looking inside the mind of a crazy lady" sort of way.
If you want a to read about a bunch of perverts ruling most of Europe, about to lose a war and therefore planning suicide, being described by a mentally deranged person, then ... this is it.