I can’t tell you how many .NET developers use Reflector. But I’d guess it’s about 99.9999999%. Lutz Roeder continuously updates Reflector as new .NET frameworks are shipped.
When you build a WPF application inside Visual Studio the compiler creates a Binary Application Markup (BAML) file. This is a binary representation of XAML auto-genned by Visual Studio. I was happy to hear that Reflector can show me the XAML for these files.
This is great news.
See my more recent post for details on how to setup up Reflector correctly to recognize BAML files.