Coming from a Nexus 6, I understand the complaints about loud speaker. But honestly, I've been impressed with the volume and quality of sound from the solitary bottom-mounted speaker on my V10. Usually when I play a YouTube video, I have to turn it down. I rarely if ever listen to music from a cell phone loud speaker.
I miss vanilla Android, but by rooting and removing some bloat and switching to the Google Now Launcher, its bearable. The second screen makes up for it. And the unlocked bootloader opens some development opportunities.
I share your frustrations and love for the fingerprint sensor, and have experienced the same three stooges act unlocking it. Part of it is due to the fact I didn't run a password or pin before, so sometimes I swipe a notification before unlocking with my fingerprint, get confused and start mashing buttons. Basically the same method I've used to play every video game ever.
But the phone is gorgeous. I mean absolutely gorgeous. So sleek. So well built. It matches the black and silver interior of my Z71, and looks like it was meant for the truck. It's heavy, but the weight is a pleasant solid heft, not an outrageous weight. Everything about the look and feel of the phone is just perfect for me.
And I have also been enjoying the camera. Having dabbled in photography with my DSLR I do enjoy the manual mode, but 99% of my photos are taken with auto mode, since they are of my dog and daughter. Neither of whom will sit still while I adjust settings. LOL
All in all a great write up, OP. And a fantastic phone. I love mine more than I thought I would.