One person says bullet everything in Powerpoint presentations. The rationale is that people can quickly view and take in a bullet point over a sentence.
Another expert I admire says NEVER use bullets. It's the death of Powerpoint. He argues for the use of images and no more than 5 words per slide. The idea is to support what you say, not parrot what you say.
Which is it?
That's for you to decide. Just realize not everyone agrees, and that's okay.