That's sort of the opposite of my experience. There are obvious cons, like (previously) having to learn a new language, Objective-C, which has it's quirks. Doc

That's sort of the opposite of my experience. There are obvious cons, like (previously) having to learn a new language, Objective-C, which has it's quirks. Documentation may not be very good in some instances. Tooling (Xcode/Interface Builder) may not be as good, or as complete, as tools like Visual Studio. But of the pros, AppKit/UIKit do A LOT of work for you once you understand things. Things may not be consistent between UIKit/AppKit due to some ability to start over a bit with UIKit plus just different form factors and things, but they are consistent amongst each other and the UI components are all very high quality and flexible. The support libraries are also incredibly good. SwiftUI should probably be labeled beta given it's not able to do everything UIKit can do, but they've made big strides with the OS releases coming this fall.