This is a minor bug-fix update. The most important bug-fix resolves a bug introduced in 1.5 where deactivating Event Organiser causes a fatal error if Event Organiser Pro is still activated. Pro requires the free version to function, but it’s nice to degrade gracefully. With this update, you won’t get an error, but instead you’ll see a warning message informing you to re-activate or install Event Organiser.
As always, point releases are focussed on bug-fixes, and you are strongly encouraged to update to the latest point release. Even if you decide against updating to the next major release.