I wasn't going to say anything about it, but since you asked.This is a really interesting conversation and one that I didn't expect. We chose the name knowing that it would turn a head or two and be memorable for it's multiple implications. The most important of which is that Facebook keeps you connected with friends and we have added so many themes and optimizations that benefit and enhance the experience.
The fact that so many of the recent comments have focused on the name makes me feel that it's a good thing... People have made a point to mention it, therefor they've committed it to memory and will recognize it when they see it in the store or remember it when it's hopefully mentioned to a friend . It kind of goes back to "there's no such thing bad press".
This question isn't intended as a jab or as sarcasm, it's genuine interest to better improve: Does the name offend anyone or turn you off from purchasing the app??
I think it's good marketing and bad marketing. There are apps that I have never looked at because of their name, and apps that I looked at specifically because of their name. This definitely could fit into either category!
I investigated it because you posted about it here. I like the app a lot and use it every day now. I went in to FB and liked it. At the same time I had also liked my daughter's church. So on my FB page it said that I "like <church name> Church and Friends with Benefits. That doesn't bother me at all - I've been known to post things just for shock value and my friends and family know that, so NBD.
HOWEVER
I am looking for a job and just recently attended a social media workshop - using social media to increase the effectiveness of my job search and brand myself. So this is where the concern lies for me. I'm not really worried about this because I think that if an employer is looking that intently into my online persona that s/he will take a look at what the app is about anyway. But it did make me stop and consider it. I am overly-sensitive right now about how I appear to potential employers and have been known to take things off of my online pages because of it.
I know that this doesn't help you much. Kinda a "maybe" answer to your question above.
But yeah, I like the app a lot.