These releases are mostly a compatibility fixers for WordPress 4.5 with a few new improvements. A complete list is available in Changelog.
If you update with normal download using WP update page, the update should work ok. If you do it manually through file upload, remember to deactivate old plugin, update files and then reactivate plugin. Simple overwriting files on disk, while plugin is kept active, will not work correctly. If you forgot, try deactivate/reactivate plugin manually once more. Pressing “Save Changes” button on Settings/Languages configuration page may also help to make the update proper.
There are probably more problems to fix, let us continue collecting the list of them on thread Issues with WordPress 4.5. Please, do not put messages there, which are not related to WP 4.5. Use the standard troubleshooting procedure instead.
The author team apologizes for any inconvenience the recent instability cased and thank all, who helped promptly to discover the problems and to test the solution.