Folks - I am the original poster on this topic and am thrilled to see all the input, albeit dismayed that so many are having issues.
I am on my second device and while the Call Failed issue seems to have subsided for the time being, audio continues to cut out and the person on the other end of the call cannot hear me.
While the majority of users experiencing issues seem to be Verizon, it could be because of Verizon's market share, as users of AT&T and T-Mobile/Sprint have also weighed in expressing similar issues.
I have been in contact with Verizon as well as Apple. Verizon attempted to fix provisioning but it is not really helping all that much. Apple may have bitten off more than they can chew with this latest upgrade.
After tweeting about these issues, I have finally gained the attention of Apple, and an Apple Engineer is attempting to contact me about this issue. Due to differences in schedules, we have been unable to connect just yet, but I am trying to make this a top priority since it is very difficult to conduct business with an unreliable device.
Once I connect with the engineer, I will be back to post if I learn anything of value.