We've had it for 5 or 6 years now. Every now and then we've had bad quality calls or the party on the other end couldn't hear us, but I think that was our cable internet and not Vonage. For the most part, we've been happy. The nice thing is that your phone number stays with your router. We started with Vonage in Arkansas and when we moved back to the D.C. area, I just plugged in my Vonage router and that's all there is to it. You could do the same if you went on vacation or something and had a hardwired internet connection. But if you wanted to change your number, I think they charge $10 or so. We decided to just keep the Arkansas number since we had friends there. All in all, I think it's a great deal. You may be able to find something better price wise, but just do your homework.
Also, if you wire things just right, you can plug your router into one of your phone jacks in the house and all the other wall jacks will be "live" so that you can put your phones wherever you want to.
And one more thing, if you know a good bit about computers, you can instal asterisk or something like that and create your own VOIP server, then find someone to give you a direct inward dialing number (DID). This could be a good bit cheaper depending on the calls you make.