I've owned both ReplayTV and TiVo. As far as I'm concerned, TiVo is the gold standard for this technology. An excellent interface and superior features.

A friend switched from TiVo to DishTV's DVR. His conclusion? "It's no TiVo."

The TiVo commercials thing is not quite what curegeorg has heard. TiVo is not going to force viewers to watch commercials. They are going to sell advertisers little on screen banners that will be visible even as you fast-forward through the commercials.