A column by Donald Norman about defending powerpoint against Tufte; some excerpts I found relevant in this informative rant:

It has become commonplace to rail against the evils of PowerPoint talks; (...) PowerPoint should be banned, cries the crowd. Edward Tufte, the imperious critic of graphic displays has weighed in with a document entitled "The cognitive style of PowerPoint,"

First point: Everyone agrees, I hope, on the undesirability of the long, boring talk in which the speaker reads things to us that we are perfectly capable of reading to ourselves. Bullet point slides often lead to poor talks, but the problem is with the talk, not with the tool. We have had poor talks long before PowerPoint. (...) Let's face it: most people give poor talks. (...) The slides are written for the benefit of the speaker. They provide an outline and reminders of what is to be said. In the worst cases, they provide everything that is to be said, so the speaker need not think, but can simply read. After all, those who suffer from stage fright, or those with insufficient command of the material are not apt to be good thinkers when in front of an audience, so the slides are a necessary crutch. The question is, if the slides are for the speaker, why does the audience have to be subjected to them? (...) 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(...) 2. Illustrative slides. These slides should illustrate the major points and help motivate the listener.(...) 3. Handouts. Here is where the speaker can put the references, the data, the appendices to the talk.

I like his final statement:

What tool do I use? Often I use no tool at all: Just me, talking alone. Technology audiences are often horrified at first, but when I am finished they are often thankful. When I have points I want to illustrate, I use PowerPoint as an efficient way of presenting photographs and drawings. I don't use PowerPoint templates. I don't use bullet points and words in my slides, not unless I must.