It's a proven fact that most of us learn better when we have something visual to engage our attention and illustrate the point being made. A well-done PowePoint presentation or judicious use of photos, models and videos can not only make an instructor-led class more interesting, but also more effectively meet the different learning needs of our audiences.
I attended a two-day forum recently (put on by a software company ironically) that demonstrated some of the pitfalls of using PowerPoint slides and other visuals to lead your presentation. From low volume levels to trouble connecting to the internet to problems connecting devices to projectors, all the little glitches left us sitting there waiting for too long and too often. Our time was wasted, plus the presenter had to adjust or cut their material to fit the time slot. I felt sorry for the presenters, but I also wondered how well some of them had prepared.A few seemed to be literally at a loss for words when the main points weren't projected 8" high on the wall, or they couldn't connect to a YouTube video. It was pretty distracting.
The lesson I took out of the two days (which by the way were still very educational and worth the time) was to be prepared for technical glitches. Print out the PowerPoint file so that you have your notes in case the iPad battery goes dead. Bring prints of any photos you use in case you have to pass them around. Post visuals (PP files, PDFs, photos, video links, etc.) online so that participants can download or view them later. Know your material well and have a backup plan. Think of alternate activities you can use to present the material and involve students that doesn't require any equipment or technology. Be prepared and get creative!