"3: Speed
Ubuntu 9.04 shows a marked improvement in both the boot process and
the desktop. The biggest improvement is with the boot process. I
have noticed the boot process of machines running 9.04 cut at least
in half. The desktop has also enjoyed a boost in speed, with
applications starting up in a fraction of their usual times. Most
notable are startup times for OpenOffice and Firefox.
"4: Cleanup Janitor
This new feature allows users to remove junk from their system to
save space. Cleanup Janitor cleans up packages that were installed
to meet dependencies but that are no longer needed, packages that
are no longer supported, and configuration tweaks that are missing
from the system. This utility will automatically find anything on
your system that is not needed and give you the option to either
remove it or fix it. You will find that a fresh installation
won’t have much cruft (if any). But Cleanup Janitor will
become useful over time when applications leave enough behind to
pile up and take up space.
"5: Nautilus encryption
This is one outstanding feature that was built into the Nautilus
file manager. From within any directory (that you have permissions
to act upon), you can right-click a file (or directory) and you
will see two new menu entries: Encrypt and Sign."