add-apt-repository for non-ppa URLs causes direct edits to
/etc/apt/sources.list. I think it's better to create separate files in
/etc/apt/sources.list.d so they can be disabled (and re-enabled) easily, and so the user is able to see what they do and don't have in their system. However, if they only ever look at the list of sources through the GUI (eg in Synaptic) then I guess it doesn't matter too much.
A better long-term solution (which I think expebition was working on) is to have a small
.deb that people download in a browser and install manually (eg by double-clicking). Installing the package would put the necessary files in
/etc/apt/sources.list.d and also add the key.
--Neil Mayhew 23:47, 6 August 2013 (UTC)