ryoung

Have had service go out on me several times over two years (at times for more than a day or two). When it's working the service is reliable and fairly good quality (better than Vonage).
Comcast Digital Voice is fairly featureless for VoIP. They do not have Call Forwarding No Answer (for services like Phonetag or Google Voice), nor do they have a Simultaneous Ring feature. They only offer the most basic of features that most companies have had for years. Their control panel is stone age.
If you can get it cheap enough in a bundle and don't require many features, then it's not a bad service. Otherwise Vonage and others have a lot more to offer.