I did an OTA update (iPhone 6, AT&T) and experienced this issue. Touch ID wasn't working and "No Service" on the phone. I tried hard resets and resetting the SIM card, with no success.
I was able to fix the issue by downloading the iOS 8.0.1 ipsw from the developer site, then connecting the phone to iTunes, holding down option while clicking on update, and selecting the 8.0.1 ipsw. Phone redid update through iTunes (not OTA) and when it restarted, all was fixed.
Not sure how non-developers can get the .ipsw file.
Not sure how I would explain how to do this to, say, my mother. Hopefully there is a more sensible/easy fix that comes out soon.
Edit: Appears to have been pulled.
http://www.redmondpie.com/ios-8.0.1-download-links-for-iphon...
straight from the apple CDNs.
Holy shit, they offer IOS 8 for iPad 2! Who are they supporting with this?
https://en.wikipedia.org/wiki/IPad_2
"After the announcement and release of the third generation iPad, the iPad 2, which continued to be available for purchase received a hardware upgrade."
http://www.extremetech.com/computing/178676-apple-kills-the-...
"In a PR statement released earlier today (March 18, 2014), Apple unceremoniously announced the death of the long-lived iPad 2. Apple’s second tablet was released back in March of 2011, and remained a core part of Apple’s line-up until today. "
Good job Apple, good job.