It is an old thing, yeah. Some interfaces are inconvenient to use and take a lot of options, most of which tend to be set to 0. There are plenty of macros and typedefs. String handling can be a bit of a pain with it's distinction of ASCII vs UTF-16.

Overall though it seems to be well documented and compared to other alreanatives more lightweight and performant. I heared it referred to as Windows world's POSIX.