I've had Vonage for 5 months now and haven't had any outages at all that were caused by their alleged incompetence.
One was ISP related where the cable service for a good chunk of Providence went dark during a snow storm. The other was a chunk of ice damaging a piece of cable on the outside of the house. Seems the methods employed by the previous building owner weren't held to exacting standards. They've got the siding off the building now so I should tack down a section of CAT-5 and replace the damaged wire. But why should I? I don't own the building and it only affected the phone in the bedroom. It also severed by connection to the NID which means there's no chance of getting a reverse voltage on my VoIP line.
I think that many of the problems people are having in the mid-west are ISP related. Therefore I understand Vonage whining about being denied access to certain ports necessary for their service to function.
Maybe I've had good luck. Who knows.