This article talks about different aspects of PowerPoint. I agree with this article, especially the fact that many PowerPoints are ineffective, as they either put too much text on slides or the slides are made without aesthetic consideration. When done well, however, a PowerPoint presentation can be extremely effective. It was the first program that was popular for people to use to make digital presentations and added so much in comparison with traditional methods such as writing on the blackboard or overhead projector. It must have cut down in preparation time as well, as it takes time for the teacher to draw complicated graphs on the blackboard or to prepare an overhead for class.
Google slideshow and Prezi are other options teachers can use, and in the future there will be increasingly more. One day, in the not-too-distant future, we will be able to display holograms for our students, or all tap into virtual reality servers. We will be able to visit a virtual simulation of Stonehenge instead of just reading about it in a book or looking at pictures of it.
I personally prefer Prezi over PowerPoint, because I enjoy creating the visual concept with which to embed my slides and it offers more potential for creativity in general. PowerPoint is 2D, whereas Prezi is 3D. This offers an entire extra dimension to work with.