I think that word has its place in certain books. In Erotica, the use of F--- is expected whereas if it's found in an inspirational romance, I definitely think the reader would sit up and take notice and may even be offended by its use.
That being said, I think in the right context the F-word would be accepted. You wouldn't expect a tough military/police officer/firefighter hero to say "dang" when something goes wrong. Nope, they're gonna use the "big" word and not be apologetic about it. To expect otherwise would be completely unrealistic. But I have to admit, I don't like the word being said by the heroine regardless of her profession. I can't explain why it seems more acceptable when said by a man other than maybe it's a product of my upbringing -- I was taught a "lady" doesn't use such language.
Will I use the F-word in my current manuscript? Yes, but only if it fits the story and character who says it.
