The OmniFocus team has been hard at work on OmniFocus 4 for some time now. Recently they announced the public release of the Beta for OmniFocus 4 for Mac. There are several significant improvements coming with OmniFocus 4:
With OmniFocus now built around SwiftUI, Mac, iPhone, and iPad features are essentially in sync. Generally, you get all features everywhere. For example, you can now get location-based tags on the Mac for the first time.
The new design is lighter than previous iterations of OmniFocus. There’s more white space, and the UI is much cleaner. Nevertheless, it still feels like a flavor of OmniFocus.