As others have said, you probably want to keep at least a regular phone line for emergencies. (I have regular local calls, no long distance carrier (by the way, AT&T is EVIL); I place a local call to a computer to place long-distance calls via VOIP. If that went down, I could use a carrier access code in case of emergency...)
That said, I just recently started using Charter High-Speed. I've only had it about a month so far, but I haven't had any problems at all. One thing to be aware of is that, when you call to sign up, they _only_ quote you their standard price--if you get a flier offering a better deal, or see something on their web site, you need to ask for it specifically. Seems a little screwy to me.
-D.