A new screen for managing extensions was added. If you previously installed extensions from FDroid, you will have to uninstall all of them first (tap on the extension then uninstall), otherwise you won't be able to update them due to signature mismatch. You won't lose anything in this process as the extensions themselves don't store anything.
The download manager has been rewritten and it's possible some of your downloads aren't recognized anymore. You may have to check your downloads folder and manually delete those.
You can now download to any folder in your SD card.
The download directory setting has been reset.
[b]Important![/b] Delete after read has been updated. This means the value has been reset set to disabled. This can be changed in Settings > Downloads
[b]Important![/b] Now chapters follow the order of the sources. [b]It's required that you update your entire library before reading in order for them to be synced.[/b] Old behavior can be restored for a manga in the overflow menu of the chapters tab.
Kissmanga covers may not load anymore. The only workaround is to update the details of the manga from the info tab, or clearing the database (the latter won't fix covers from library manga).