It's really bad, actually. But it's the best we've got.
See also UsingTheMouse.
I would say it's probably the best interface possible given the input/output hardware that we have. Getting other input/output hardware sufficiently popular to warrant new interface designs is an expensive venture. -- SunirShah
Don Gentner and Jakob Nielson had some interesting ideas about this entitled the AntiMacInterface. They suggest a combination of GUI and CLI, with an interactive element to the CLI - so that you can work with it and refine things, instead of making repeated trial runs. All in all very interesting. (personally I feel that a WIMP interface gets in my way much more than it helps - it actually hinders expert users) --ErikDeBill
"A mouse is what you use to show which Xterm you want to write in."