I dunno, looking back I don't think that soap was really the problem. I'd see people complain about how complicated soap was while not using a library for it. Then say REST was so much easier as they piped the JSON through eval to get things working.
Ahah. In my days SOAP libraries were kinda shitty up to the point I had to write my own to handle "non-standard" (actually very standard) WSDL definitions. SOAP consumption in one lang was okeish, especially Java or .NET. But interop — oh boy. The biggest issue were services exposing SOAP interface based on code-first approach, when you write some declarative code with annotations and library transforms it into WSDL and proxy endpoints.