1. No one but the Creator understands their internal logic.
2. The native language they use to communicate with other computers is incomprehensible to everyone else.
3. The message "Bad command or file name" is about as informative as, "If you don't know why I'm mad at you, then I'm certainly not going to tell you."
4. Even your smallest mistakes are stored in long-term memory for later retrieval.
5. As soon as you make a commitment to one, you find yourself spending half your paycheck on accessories for it.