Well, if the scan freezes and battery is being drained, it's a bug, not a feature that crept there together with the premium features.
The UI is not ruined, we simply left the features that are being used the most on the dashboard and put those less used to the side navigation. We understand that not everyone use the product in the same way, but we're trying to satisfy as many users as we can. With the number of features growing, the list UI we used before would get too cluttered and confusing. I know it may sound surprising, but many people want the Virus scanner, not a Swiss army knife, so we cleaned it up a bit.
There's no separate premium app, because we don't want to shatter our user base. And it's much more convenient for the user to upgrade to premium, whenever he feels like it. You can always use the free features, and when you feel you'd need something more, you don't have to uninstall and install something else again.
There's no way of buying the old version, unless you find the APK lying somewhere on the internet.
But, it'd be much more helpful to actually help us fix the problems you have (virus scanner and battery drain), rather than to pronounce as doomed and leave. If you want to help, let me know and I'll tell you how to send us the information we need. We're aware of the Virus scanner issue, but so far we weren't able to reproduce it ourselves.
Thanks,
Ondra