Win32 is definitelly an obsolete technology and making GUI with it is much less comfortable than with any newer technologies like Winforms, Java or QT. Win32 GUI offers just about 25 visual components in total, their functionality + look and feel are very mean.
However Win32 GUI has an advantage that you don't need to download anu third party library and exe file is very small. Therefore such GUI is acceptable for writing test applications for you C++ libraries where ugly GUI is not a big deal.
This project shows how to do such simple ugly GUI.