I upgradet my notebook to openSuSE Leap 42.3 with zypper dup and everything went well. It took only a relatively short time in comparison with an upgrade of MS Windows and I had not to restart my box several times.
The upgrade needed only some edits to the software repositories that I used for the notebook. Nearly all of them needed only a change of the version number in the URL Form 42.2 to 42.3. The LibreOffice Factory repository (needed especially for building) needed a different tweek. There is no sub-repo for 42.3 yet. This I had to change to the sub-repo ‚openSUSE_Factory‘ instead. That was all I had to do before I run the zypper dup command.
Really easy to update the Linux distribution. And I had not to reedit my user configuration etc. Everything works AS before.