They might allow you to have the TiVo free of charge, as in perhaps no installation fee, but is there then a monthly cost for the service or that you have also got the V+
But TiVo, once you are used to it is a bit improvement on the V+.
Three tuners allow you to record 2 programmes and watch a third live, or record three things at once whilst you are watching something already recorded. V+ only has 2 tuners.
Increased hard disk capacity
Series links are far more intelligent, along with wish list and other search by programme name, artist, etc will check current, On demand and future show matches.
The EPG covers more days and shows the previous days so you can see what you just missed.
Suggestions records stuff, subject to disk capacity, based on your likes.
About the only thing I don't like is the EPG guide insists on defaulting to every channel listing, rather than just the favourites, that the V+ lists by default.