I don't watch pron on my iPhone
I don't have super secret text, emails and images on my iPhone.
I don't have super important data on my iPhone. If people want to peek over my iPhone, I'd easily conceal it, and luckily no one crazy enough or have time to peek over while I'm doing something on my iPhone.
If someone happens to peeking on my phone, it's not my goddamn fault, I'd shoo him and simply say mind your own business, mate. He must've too much time with himself.
I don't know about BlackBerry or Android handset, but I'd never use privacy film with awesome iPhone, it's kinda defeat the purpose of having IPS display on it, plus it decolorizes the screen in a bad way. Why would you sacrifice that?
If I wanted to have a narrow viewing angle so people won't peek at my phone, I'd settle with cheapo phone with TN display, why settle for the best?