What disturbs me is the apparent focus on deviant sexuality and "kink". I don't know about others, but I view bondage, S&M, and other fetishes as disturbing to say the least. I don't find any of the aforementioned "kink" erotic at all. I find a fully clothed woman in a revealing position a lot more erotic, than a naked one tied up being beaten.
With that said, I can see a book detailing love and romance, even sexuality to an extent, in a fantasy millieu as interesting and worthwhile , even if I wouldn't personally buy it. Afterall, love and sexuality are themes of many great epics. However, from what I've heard BoEF doesn't cover any of this. Instead we get PrCs for S&M, sexually active monsters, and "sex magic" (I scored last night so I can now cast spells at with a higher effective caster level. Hehehe).
Also, what's with the digital photos? Do we really need to see photos of nekid elf babes in a game manual? If I want to excited, I'll get a real porn magazine, not a game manual.
The d20 market is really getting interesting now that we're getting some niche products like this. I just don't want to see what's next.
Disclaimer: I haven't seen the actual BoEF yet. All my information comes from the what I've heard from others.