From In Defense of PowerPoint, an essay by Don Norman
Readers should get good clear information, with sufficient background presentation that they can re-interpret and re-analyze the material presented to them. Readers are not listeners. This means that speech giver should really develop three different documents.
1. Personal notes, to be seen only by the speaker, and used as a reminder of the topics and key points, or perhaps of the "bon mot," the clever, felicitously worded phrase that can appear spontaneously witty to the crowd, but which works best if it is prepared and practiced in advance, for few of us are good enough to actually think of them on the spot.
2. Illustrative slides. These slides should illustrate the major points and help motivate the listener. Tufte is apt to complain that this is simply "entertainment," but I respond that if the audience is not entertained, they are not apt to listen, and what good is a cleverly drafted talk if the audience is not listening. The illustrations should be relevant. They should convey new information. But they need not have words. They might have data, they might have graphs, they might have photographs of the product, equipment, phenomenon, or other aspect of the point under discussion. They should add to the talk, not distract from it.
3. Handouts. Here is where the speaker can put the references, the data, the appendices to the talk. Here is where one should indeed follow Tufte's advice and provide clear, detailed information that the reader can use later on to remember the points of the talk as well as to go on to further study and analysis.
Three separate and very different documents: Personal notes, illustrative slides, and handouts.
Don't confuse one for another. And don't blame the tool for a poorly prepared, poorly presented talk.