I think the killer feature is that it will work on any platform with a decent webview control (Windows will finally be joining that club soon when WebView2 ships in-box), including MAUI; so you can use the native hosting bits of MAUI and the web UI bits of Blazor, no XAML required. And then you can reuse that same UI on another platform or a web browser, trivially.
Hot reload for Blazor dropped in the recent .NET 6 preview 3 so this is a really good time to get started with it. It blows XAML Hot Reload out of the water because it can reload many C# changes in addition to HTML/CSS changes; XAML Hot Reload breaks down as soon as you need to change any C# code that touches your UI.