I have seen both the good and the bad side of PowerPoint/slideshow-like presentations while attending a university.
My art History professor did a great job of using PowerPoint effectively. Each slide contained a few images of statues, paintings, or buildings. Next to each image there were a few quick facts such as a the year the piece of was made and the author's name. He never read from the presentation; he used PowerPoint as a tool to help facilitate learning.
On the flipside, my chemistry class was one of the most abysmal experiences of my life. Before the semester began, every student purchased a packet of fill-in-the-blank notes. Every class period - and I mean every class period - the professor would put up an identical page and read through it while filling in the blanks. We were supposed to follow along and fill in our notes; most people just slept. I sat front center and I still was bored out of my mind.
Slideshow presentations remind me of going to a planetarium. You look at a large, pretty display and listen to a voice that has no head. People learn best from other people and interacting with them, not from a computer.
PowerPoint Kills Brain Cells