After two months, I have mostly good things to report on the TiVo. Its ability to predict what I might want to watch is so good as to be unnerving. Several times I went to manually record a program and found that I could rewind back through the part of the show from before I started recording it. The TiVo anticipated I wanted the program and had already started recording. In other cases I couldn't rewind live, but could do so several days later (I assume the TiVo filled in the missing bit from a repeat).
The "Wishlist" function to find programs on topics works well. I have an interest in trains so asked for TiVo to record train documentaries. I thought this might take months, but within a few days the TiVo found an episode of a travel documentary which featured a train.
There have been some problems. I found once or twice the TiVo was recording the same show using both tuners simultaneously: one on standard definition and one high definition. Most of the time this is not a problem, with the guide indicating that these are the same programs so only one version gets recorded. To eliminate the program I decided to delete the HD channels, as these look no better on my small screen than standard definition. But I then found the HD channels kept reappearing the next day. After several deletes the TiVo seems to have got the idea I don't want HD.
Also I have had a problem with the remote control not responding a couple of times. The amber light on the TiVo flashes to indicate that the box is receiving signals from the remote control, but their is no response to any buttons pressed. The only way I have found to fix this is to turn off power to the box and restart it. After a minute the TiVo reboots and everything is fine for a few days.
However overall the clever interface makes me wonder why all PVRs are not like the TiVo.