If you updated to iOS 8.0.1 on Wednesday and you are having problems with cellular service and Touch ID, Apple has posted a support article detailing how to downgrade to iOS 8.0. It’s a fairly easy process using iTunes.
Of course, the upside of losing cellular service on your phone is the battery lasts a long time.
Apple has released the 8.0.2 update. The issues with the 8.0.1 update only affected iPhone 6 & 6+