The human brain can be understood as a kind of organic data-processing mechanism. Normally the data it processes is derived from sensory input as well as its own analysis relating to that data, however simple or complicated the analysis may be. LSD produces a random stimulation of the brain that does not derive from sensory input, although it does typically alter sensory input. So you can still see when your mother walks into the room, only now she might appear to have green skin and tentacles growing out of her ears (or something like that).

There are many different kinds of reactions that people have to LSD. Many people find it to be highly inspiring, and an enhancement to their creativity, but some people experience paranoia or other mentally unhealthy states. So, it can be a good thing, but there are risks. Naturally I would not advise anyone to break the law by using a controlled substance without a doctor's prescription. However, just as society is re-assessing its attitude toward marijuana, I expect that society will (sooner or later) also re-assess its attitude toward LSD.