I'd say you haven't looked then.

Silverlight is well done. It isn't a half-assed idea. The separation of xaml from viewmodel (using the MVVM pattern) is clean. You can unit test the shit out of everything. The commanding system and data binding implementation is beyond any other tech I've seen. They took the best parts of web dev and desktop client dev and made it work well. Combine that with the .Net framework and the fact that you can develop in a variety of languages and you have a winner. Say what you will about Microsoft as a company but their developer division is sharp. The tools (Visual Studio and Blend) are great too.