I have utilized Vonage for my home office for the past year and a half. In that time, I figure I have saved about $300 from my previous service with Bellsouth/AT&T. However, the 4th broken VOIP device in that period was enough to make me switch. I recently lost service on my most recent Vonage device on Monday morning, which, of course, is probably the least opportune time. Using your cell phone for business calls teaches a person to move service to a reliable provider. I was more than patient, as most people would have canned the service after 2 failed devices.
I have chosen a new VOIP provider and will review that one after several months.
Vonage has a nice billing platform, good features, but could not deliver reliable VOIP service to me overall. Reliability is key.

Happy Thanksgiving!
Eric