I watched a total of four presentations and did one myself last Friday. Out of the four presentations that I saw, three were group presentations done for course projects, and the other one is a solo presentation done by an engineer in IELM311.
In the group presentations I watched, there was one presenter that was extremely remarkable - remarkably bad and unnatural. Good presentations feel like an old friend talking to you, even though you've never met the presenter beforehand. This guy... he spoke "perfect" English during the whole presentation, more perfect than native speakers - there was not even the slightest pause in his presentation. He just kept talking talking and talking, jumping around mechanically as if those were gestures, with a smile always so wide on his face that he looked schizophrenic.
But aren't these stuff what our English teachers taught? Of course, nobody taught you to deliver your gesture mechanically, yet there's always somebody who goes too far in following those lessons.
The presenter on Friday got me recalling another presenter I saw when I was in a public speaking competition in form 6 - there was another presenter from another top secondary school that acted exactly like him. That presenter also spoke perfect English - with appropriate pauses this time, even. But there was something very unnatural with him - his body was swinging like a pendulum the whole time during his presentation. Looking at him makes you feel like attending a rave party. The judge (who was a foreigner) gave him a very low grade as a result.
What is a good presentation? I've seen good and exciting presentations where the presenter didn't even speak good English (e.g. Tam Wai Ho's presentation in IELM311). The differentiating quality between good presenters and mediocre presenters is their ability to make the audience feel comfortable and keep them thinking instead of falling asleep. When you're seeing a product presentation and you're thinking, "Hey, this product seems amazing, what uses do I have for it? How did they do it? Are there any modifications that I'll need if I were to buy it?", then you're looking at a good presenter. This unique quality cannot be emulated by simply speaking good English (you can even do without that) or having tons of gestures in your presentation, as your English teacher would have taught you. But how did the good presenters do that? I wish I know. But understanding the audience should be the first step, since a good presentation directs the thoughts of the audience.
Where are the good presentations? Apple have them.