I have a comcast DVR hooked to a Sony TV with the HDMI cable. Works fine. The only down side is when switching inputs it takes a couple of seconds for the TV and the DVR to finish their hand shaking. I suspect it is the beginning of the end of copying anything. (The sender box won't transmit unless it is assured the receiver will honor copy protection.)
To be truthful, I can't tell the difference between it and s-video. The biggest determinate of quality seems to be the source of the video not the cable to the TV. The colors seem to change slightly (I suspect color information is passed to the TV). But, I can't tell which set of colors is "right" or better. It is just slightly different.