I just signed up for the Comcast Triple Play, which combines high-speed Internet access, digital voice service, and digital cable for $100/month. It was installed about five days ago so I've had a chance to get familiar with each of the three services, and so far I'm pretty happy with it.
The big advantage of the digital voice service is the price - as part of the package, it's only $33/month for unlimited local and long distance, plus a bunch of features like voice mail, call waiting, etc. You can even check your voice mail over the Web, which might be useful. Given that no cable installation ever happens without problems, however, the cable guy somehow forgot to turn on my voicemail, and I'm still trying to get that worked out. The overall sound quality is OK, although theres a slight but noticeable hiss in the background.
The Internet access is OK, but it's not as fast as the DSL I had before, so I'm a little disappointed. More accurately I should say that it's fast but not quick, meaning that jumping from page to page is slower than I'd like, but once I'm downloading a big file it really moves.
And cable is cable, no surprises there. So overall I'm satisfied that I'm saving money by getting all three services together and that things are working OK, but there's still room for improvement.