MVP had been the dominant presentational pattern for most UI development, with MVC still having a strong presence in web UIs before .NET 3.0 introduced some new technologies that made MVVM or Presentation Model an attractive option for WPF and Silverlight.
The benefits of MVVM include the following:
- Increased testability: Testability is improved as all view logic is now easily testable from unit tests.
- Less code: I've found that the amount of code required to manage the view has decreased quite a bit, as you no longer have to deal with boilerplate code behind code. This code involves a lot of casting and error checking in production quality code. Less code means fewer bugs, less code to maintain, and fewer unit tests to write.