Obviously this is a personal preference thing but I look at my Comcast HD DVR and see, after the recent holiday season, that the 'now playing list' is empty (well, one old episode of Malcolm in the Middle, but...)
I look at my Tivo, however, and it has a dozen screens full of things to watch, some of them interesting.
The alternative is channel surfing, something I haven't done since God invented Tivo.