This functionality is included by default in the desktop version but needs to be added to the server version.
For that and other reasons Debian does not keep up with the "upstream" newest version or programs.
Once a distribution is released, the software is kept at the same version, and only security bugfixes are released.
The Software Updater cannot uninstall updates, although this can be accomplished by other package managers such as Ubuntu Software Center and more technically advanced ones such as Synaptic.
In Ubuntu, the Software Updater can update the operating system to new versions which are released every six months for standard releases or every two years for Long Term Support releases.
On the other hand, you risk occasional unstability and possible unpleasant surprises, when things suddenly stop working the way they did before, because a new version of some package was added to the testing distribution.
You can somehow mitigate this by only installing some individual packages from the testing, unstable or experimental distributions, which is what thiton suggests. Another possibility, if you want to use the newest version of some software, is to manually compile it yourself, and install it in the , so your manually installed software will not get overwritten by the official version when you update your system.Sometimes, a revised package will require the installation of a newly revised version of another package, in which case the installation will fail until/unless the other package is installed.Many people find this approach much too time-consuming, since Debian evolves so quickly -- typically, a dozen or more new packages are uploaded every week.You should also read the Release Notes document that describes the details of specific upgrades.It is available on the Debian website at will install upgrade files in place, even on a running system.Many people, however, successfully use the testing distribution in their daily work.