Documentation is a problem.
Although the X Window System as distributed by MIT and most third-party vendors includes a sizeable body of online reference materials, they are difficult to locate and still harder to use. The documents assume that the reader already knows the system and requires detailed information on options available for a particular feature or subsystem. A few demo programs illustrate specific aspects of X, but virtually no tutorial information is available. Most users are forced to learn X through oral tradition. For the benefit of the first-time user, all assumptions are clear from the outset.