Strangely, i've got the V+HD box and really like it. Performs very well and easy to use, but most of all the remote is really good (i hate remotes that you have to look at the buttons before you press when they're ilogically laid out).
My parents have the Tivo box which i dont like at all. Hideous red menus, very small writing on the onscreen menus that my mum cant even read, and you dont appear to be able to change, and it keeps recording suggested shows for them, which theyre having to frequently delete (although you may be able to switch this off).
The only thing that annoys me about the V+HD is that at midnight every night it updates itself, and the remote stop responding!!