A quote from Chapter 14 of Zen and the Art of Motorcycle Maintenance:

"Peace of mind isn't at all superficial, really," I expound. "It's the whole thing. That which produces it is good maintenance; that which disturbs it is poor maintenance. What we call workability of the machine is just an objectification of this peace of mind. The ultimate test's always your own serenity. If you don't have this when you start and maintain it while you're working you're likely to build your personal problems right into the machine itself." ... "It's an unconventional concept," I say, "but conventional reason bears it out. The material object of observation, the bicycle or rotisserie, can't be right or wrong. Molecules are molecules. They don't have any ethical codes to follow except those people give them. The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquillity it's right. If it disturbs you it's wrong until either the machine or your mind is changed. The test of the machine's always your own mind. There isn't any other test."

I find this true, not just for machines, but also software and the web.