Upgrading Piwik from 2.12.1 to 3.0.3 - Any known issues or considerations?

We use Piwik 2.12.1, running under Apache 2.2 on Windows 2008 R2. We would like to move Piwik to a proper Red Hat Enterprise Linux 7 server with apache 2.4, and upgrade it to version 3.0.3 (or install fresh and migrate the data, whichever).

The update documentation and FAQ states it’s possible to update from any version to the latest, but just in case, are there any known issues or considerations to go from 2.12.1 to 3.0.3?