Phone is great so far - the one thing that really surprises me is how effective the iris scanner is. It's truly great. When I set it up a couple hours ago, I was super pissed because my security was being bypassed and the phone unlocking when I woke it...turns out it was just scanning my irises so fast I didn't notice.
If you're walking or in a car, it takes a couple seconds...otherwise, it's nearly instantaneous.
So far, I've only used my FPS for LastPass logging in, although with sunglasses I will have to use the FPS.