I had less issues with TouchID on my iPhone 6 than I've had on my iPhone 7 for whatever reason. My hands get pretty oily for whatever reason, the sensor on the iPhone 7 is a lot more picky and I regularly find myself either needing to wipe the home button and my hands down or just sucking it up and entering my passcode.
I'd really like to use a longer passphrase to protect my phone, especially now that iOS 12 has the USB locking feature to protect against threads like greykey - but it's a huge pain in the ass to enter a sufficiently long or complex password or passphrase on a touchscreen keyboard so I haven't bothered due to the aforementioned TouchID issues. I'm actually kind of looking forward to upgrading this year and giving FaceID a go, it's annoying that I have to trade the option of using TouchID for it but all the anecdotal evidence I've found presents a more consistent experience.
I'd really like to use a longer passphrase to protect my phone, especially now that iOS 12 has the USB locking feature to protect against threads like greykey - but it's a huge pain in the ass to enter a sufficiently long or complex password or passphrase on a touchscreen keyboard so I haven't bothered due to the aforementioned TouchID issues. I'm actually kind of looking forward to upgrading this year and giving FaceID a go, it's annoying that I have to trade the option of using TouchID for it but all the anecdotal evidence I've found presents a more consistent experience.