What amazes me about Microsoft operating systems
is their total disregard for security, expandability, and even functionality. The hardware requirements roughly double with each release of the OS. The software for the OS is typically incredibly inefficient, and the source isn't open so people can't optimize it even if they wanted to.
Windows is called a "toy operating system" for this reason. Its memory protection, where it exists, is horrible. Its security is totally nonexistant. Microsoft keeps releasing standard software with security holes all over it. It doesn't have some of the incredibly useful features that most X11 window managers have, like multiple desktops. Nothing for it is open source, except for the occasional odd piece of software floating around somewhere. Most users I know who know something about computers, know how to program, and aren't forced to use it and don't have an definite economic interest in using it, don't. They use it for games. Hence, it gets called a "toy operating system".
Some of the things that Windows does tend to do a lot better than other OSes like Linux and BSD:
High performance graphics support. It really isn't here in X11, though this is changing.
Driver support for hardware from manufactuers who refuse to release their specifications and refuse to release a driver. (Or release a driver which is binary-only, which most people won't run for a whole slew of reasons.)