> Except, on occasion, where it just silently replaces some vital
> configuration file with a non-working version. Fortunately, that does not
> happen very often, but there is a much more frequent problem which
> afflicts all Debian-based distributions: it will often stop and ask what
> to do about configuration files which have never been changed by anybody.
Both of these are usually due to packaging bugs.
> Ubuntu has, unfortunately, earned a bit of a reputation for
> upgrade-related problems; somewhere in the process of civilizing Debian,
> that distribution's robust upgradability has suffered.
It's an old myth that Debian's quality is mainly due to dpkg and APT. It's
mainly due to packaging policies and practices.