The two best things about swift UI are live previews and Declarative layout.
This year at WWDC Apple introduced Swift UI and Combine, two new ways that go hand in hand to develop applications for all of their platforms. I've already written about them at the unveil, but now I had some time to digest them. I'm confident to confirm what I've already said at the beginning of June. Even though most developers can't afford to use them right away since dev shops usually support at least -1 version (sometimes even -2 or -3) of the OS and both Apple UI and Combine are exclusives for iOS 13+, they are the future of iOS and mac development and they will eventually replace AppKit and UIKit in most apps.
It might be overwhelming at first for someone used to the traditional Apple way of MVC and imperative programming to switch to reactive and declarative. It still is for me. All is still very new and overwhelming. The secret is that you don't have to tackle it all at once.
You can first start with SwiftUI only and use imperative programming with it. Once you feel confortable you can start trying Combine out to close the circle.