UIKit has a few frustrating details, but overall it stands tall above the competition.

For a long time the main downside was that you had to deal with Objective C, which is a turnoff for some people.

Swift solved all this, and writing UIKit in Swift is mostly a joy. Sadly now SwiftUI is the new shiny thing, and it’s a major downgrade in most dimensions save for a few.

A cross platform framework that reuses UIKit conventions and supports all modern languages (C++/Rust/Go/Python/Nim) would be the dream.