Try a search on Silverlight - lots of info out there.
Is it a success? In my opinion, not yet. To complicate matters, Microsoft as shifted focus a couple time regarding Silverlight. Here is one article to get you started: The future of Silverlight and HTML 5 at Microsoft - Microsoft
Microsoft has pulled the plug on products/platforms in the past, leaving developers in the dark with no support (I got burned in the late '90s). Some developers are naturally reluctant to invest too much time on Silverlight.