Can I see more details of an aptitude dist-upgrade? [duplicate]
If you install the apt-listchanges package, you get more options. You can get apt-get and aptitude to show the changelogs of updated packages (either the full changelog or just what's new in the upgrade), and to prompt for confirmation after you've seen the changelogs. By default, after you install apt-listchanges, only important news are shown; to see changelogs, run dpkg-reconfigure apt-listchanges.
In Debian, the related package apt-listbugs fetches bug reports from bugs.debian.org. I'm not sure if it's been ported to look at launchpad.net for Ubuntu.