Yeah I remember doing that in one project. And then at least I found c++ and ATL back when it came out. I never went back to doing COM in C after that.
Painful. A lot of the Microsoft interfaces these days are asynchronous and are built around the dev experience of c#/c++ with libraries/runtimes that do a lot of the heavy lifting. So you end up calling functions with ridiculously long names and they aren't like good old win32 calls where you pass in some parameters and you get a result back. Instead you create objects to pass function pointers and data around and who knows when you'll get your result values back.