Powerpoint is an outstanding tool, but it is heavily overused. In my Captains Career Course class, we were PP’d to death many times per day, then one day we had a power outage during a pretty technical class, and the instructor just went to whiteboard and marker. That was probably the best class we ever had. Powerpoint’s rigidity was completely eclipsed by the ability to correct any unclear diagrams or ideas with the good ol’ whiteboard eraser.
Here's an excerpt from the "Cognitive Style of PowerPoint" essay linked above:
My personal most hated is when the presenter reads the PP to you. That should be grounds for an instant demotion or firing.