The Win32 port of Icecast 2 is a simple command line application, it used to be a UI framework around the core Icecast 2 server.
The GUI is no longer necessary as Icecast has achieved all of its functionality in its web interface.
Most of the features of Icecast 2 are available in the Win32 port.
A notable absence is IPv6 support.
We are planning to reintroduce the capability to start Icecast as a Windows Service in the 2.5.0 release.