Huge downside to no fingerprint on the 4

Just to play devil's advocate for a minute, I'd point out that a lot of the situations you use to illustrate, you might also be wearing gloves. Motorcycling/skiing.
Sure, but the scenario is I pull off the road to check my phone for messages, or a map, or to take a photo and I currently only have to pull off one glove and boom I'm into the phone. Or skiing I'm on the chairlift and want to see where my wife is on the hill or to take a photo, so again one glove off and I'm done. Taking the helmet off and putting it on again would be a huge hassle and not something you can do in a few seconds. Like I wrote, it looks like it will be back to using a short PIN, which I assume will still be an option.
 
Just to play devil's advocate for a minute, I'd point out that a lot of the situations you use to illustrate, you might also be wearing gloves. Motorcycling/skiing.

I jumped on these when they came out on Kickstarter a few years back - they work great with gloves (well, at least with capacitive FPS. Haven't tried with in-screen). Not sure if they are just temporarily out of stock or now defunct, though.

https://www.nanotips.com/products/taps-touchscreen-sticker
 
Another thing is I don't always want my phone to unlock when I look at it. For example, when I am in a meeting I often put my phone face up on the table so that I can keep track of the time and watch for any important messages. But, I rarely want the phone to actually unlock during the meeting. Or, at night, when the phone is next to my bed I like to be able to glance at the time if I wake up--wouldn't want to unlock and light up the room if I did that. Am I missing something?
 
Another thing is I don't always want my phone to unlock when I look at it. For example, when I am in a meeting I often put my phone face up on the table so that I can keep track of the time and watch for any important messages. But, I rarely want the phone to actually unlock during the meeting. Or, at night, when the phone is next to my bed I like to be able to glance at the time if I wake up--wouldn't want to unlock and light up the room if I did that. Am I missing something?

Yes, that's what motion sense is for
 
Thinking back to when face Id launched on the iPhone apps were pretty quick to support it but it was not instant. Let's not forget the fragmentation complication too and the fact that P4s will represent a low proportion of droids out there. My gut feeling is that it could be quite a wait for some apps. Let's see.

Either way I am actually tempted to pick up a 3, 3 XL or 3a XL.
 
Probably will work, a lot of my Apple apps still show touch ID as the unlock method but it uses face ID.
Several of my more sensitive secure apps: credit card, bank, use fingerprint scanner to open the app. Maybe they will go to face recognition at some point. Who knows. I think it's a deal killer for me.
 
Yes, that's what motion sense is for
I guess I would have to test, but what happens when you roll over at night and reach for the phone to check the time? Does that trigger the face unlock? Or, in the meeting when I reach for the phone to check the time? Seems to me that will trigger the unlock, but maybe I am wrong. I want to only unlock the phone when I want to unlock it, not when the phone decides to unlock. And, apparently the unlock works even when your eyes are closed, so if I roll over at night and face the phone will it unlock automatically?
 
The fingerprint worked so well on the 3 but from what I see the Face ID is faster on the 4 so good job google.