I just updated the plugin from previous version (directly to 2.5.1).
I discovered that the settings section was empty (previous settings were lost). Then I reconfigured it and discovered the settings were not saved (I tried several times with different browsers).
Then I unactivated the plugin and then reactivated it .. now settings are saved but the demo link does not work anymore. Plus even if I flag "splash image activated", It does not work (I checked dates) ...