I recently decided to take the plunge and purchase a residential VoIP service. My first choice was AT&T CallVantage based on their top score in a recent CNET test, but when I tried to sign up on their web site I received a notice stating that they didn't support E-911 services in my area and thus couldn't provide me with service.
I then tried signing up for VoiceWing (same price as Vonage, more stable business). Verizon's web site took my order but with a disclaimer that if they couldn't verify if 911 support was available. The disclaimer stated that if it wasn't available, they would refund all charges and cancel the order. Three days later a box arrived containing a LinkSys ATA that was about the size of a deck of cards. After less than five minutes of setup time the service was active and has worked flawlessly, though their web site is slow as molasses and all the help pages seem to repeatedly time out. The only other real complaint was that they didn't provide any instructions on how to access voicemail (which is why I was trying to access the help pages). However a five minute call to one of the most pleasant tech support people I've ever met got me all the info I needed to get my voicemail account set up. Call quality has been very good, and I'm loving the fact that I can send voicemail to e-mail and simultaneously ring my cell phone.
So I've jumped into the world of residential VoIP after using an IP Centrex service at my office for the last five years. Let's hope the experience continues to be pleasant.