Well if it is any help, I have an iphone 4 on verizon that I have had since verizon's launch and I have recently began getting o's for 3g service (never happened before) and low bars for signal strength. I have had no problems before the last 3 weeks and have had verizon for over 10 years. I personally do not believe it is an iphone 5 issue as my best friend has that phone on AT&t and is not experiencing that problem. On august 30th, I lost complete signal and 3g at my work and again this past week. Early this morning I again saw a "o" where 3g is supposed to be at my home and a couple hours ago, I had 2 bars service at my home. I usually have 5 bars here.
I personally believe it is a verizon problem and not an iphone 5 problem. Especially since the problem was fixed everytime after calling verizon. Worth mentioning....On the august 30th issue, I also lost dial tone to my verizon landline at my business. I am in a strip mall and every other business with verizon also had either no dial tone or echo in their phone instead of dial tone. Amazingly, the landline and cell phone were fixed at the exact same time.
Also, it could be a matter of verizon and at&t carrier issues depending on where you live and what they are doing to their lines. At this time, I'm not too happy with the verizon service I've been getting lately for the price I pay them.