The speed and display as well as usability of other x applications such as xscreensaver

The fact that XServer is open-source is the biggest positive it has, it started with pretty humble beginnings and has transformed over the years to a fully featured, low resource intensive, Display Server, able to run a window manager ( Graphical Display Interface) that offered users a alternative to CLI when using Linux kernels, In my opinion, X server played a integral role in the popularity and usability of Core Linux.

It is a free, maintained solution providing the basis for *nix GUIs. I have used it my entire career for interacting with my *nix computers. I have used it on Red hat, opensuse, slackware, Solaris, and HPUX. I have used it with CRTs and LCDs. I have used it to display GUI screens over local lans as well as over the internet. I have used it with Nvidia, Matrox, Intel, and AMD video cards. It works everywhere!