For example, doesn't Tivo automatically record shows it thinks you would like.
Those are "Suggestions" which work poorly at first but after you start watching more shows and rating shows you like with a thumbs up, or ones you do not like with a thumbs down, it'll get more accurate in what it records.
I find I rarely have time to watch anything from the recorded Suggestions but from time-to-time will find a gold nugget in there - such as Amazing Race which I never bothered watching until I watched an episode that was in Suggestons - now I'm hooked.
If your looking for an HD unit TiVo's out. They won't have their HD unit out until the 2nd half of 2006.
Comcast also has a dealie with TiVo in the works where the TiVo software will be used on their DVRs but again no exact dates have been given when that rolls out.
I guess another plus for TiVo, and I don't use it for this but know many who do, is that you can hook it up to your network (provided you find a working adapter) and can transfer shows from the DVR to your computer or vice versa.
There are some other minor neat TiVo functionalities too such as when fast forwarding the show will actually jump back a few seconds when you hit play button. That way you don't miss a thing coming out of commercial whereas, I believe, other DVRs just start playing where you hit play (which could be several seconds in to the show).
Whatever choice you make DVRs are pretty cool. I didn't buy in to the whole notion it would change the way I view TV until I got one and found out it had.