Let me first say that I think Face ID will function as advertised. That's not my issue. My issue is that there are specific situations where the phone isn't in my hand and getting my face where it needs to be simply won't work. Some examples: I'm in meetings all day and frequently need to quietly check an email or two; Face ID would require me to pick up the phone to look at it or lean forward in an obvious manner, tipping off the person speaking. I commute by car each day and use a vent mount to hold my phone; Face ID would require me to do neck gymnastics to get my eyes oriented over the center console to unlock it if I'm getting gas or am parked in a queue to pick up my son after school. At my desk, my iPhone lies flat about 8 inches away from the keyboard. To wake the phone I merely press the home button. To unlock it I keep pressing. With Face ID to wake the phone lying flat on the desk I need to use my whole hand to grip the phone and hit the side button with my thumb. If I then want to unlock it I need to pick it up and point it at my face. I have a beach house and am full of sticky sunscreen and sand as I sit in my chair with my phone lying flat on the armrest. With Touch ID all I have to do is keep my pointer finger clean to unlock the phone. With Face ID I have to grab the entire phone with my dirty hand, get the case full of oily chemicals, and get the case full of gritty sand merely to check for a text message notification which I tend to do every 15 minutes. I use Apple Pay constantly and the new behavior adds steps and complexity. With Touch ID all I have to do is slide my hand in my pocket, pull it out by the thumb, and before the phone hits the wireless terminal it's already unlocked and authenticated. With Face ID it takes twice as long to double click buttons, raise the phone to my face, etc. I'm not afraid of the technology. I believe it will function as advertised. What I'm saying is that there is nothing convenient about Face ID except almost exclusively for situations where the phone is in your hand. And for my usecases at least 50% of the time my phone is not in my hand when I need to unlock it. So it will prevent me from buying a X. Which is a shame because I like the new screen and I like the new gestures and am bored of the 6/7/8 form factor.