Released on December 6th, 2014.
This is a stable release and is recommended for all users.
For a while this release was going to be called 5.1.3-stable but, as it includes a small database upgrade for best stability, we named it 5.2.0-stable, in order to signify that you need to perform a quick run of the installer, even when upgrading from 5.1.2. Rest assured though that this is majorly 5.1.2 with many many bug fixes, so it's actually super stable at this point! ;) Upgrade is highly recommended for all users.