It really wasn't all that great during the first couple years. And it still has a few annoying caveats today. The advertised flexibility (port sharing etc) most probably wasn't the only reason for http.sys back in the day :)
EDIT: that is not to say that it is as horrible to use as epoll (at least in multithreaded programs), but my favorite has to be kqueue.
EDIT: that is not to say that it is as horrible to use as epoll (at least in multithreaded programs), but my favorite has to be kqueue.