It's a bullet point, not a paragraph
OK, so maybe that's taking it a bit too far. I hate it when people make me read slides. Who wants to see this:
Nobody does. You can't just scan it and get the salient points. It invites the audience to read instead of listen to the speaker, who now has nothing of substance to add because all of the information is there already.
When you have a text-based slide to present, you have to keep in mind that you aren't writing an essay, you are presenting information and want people to follow along. In Part 4 - Text based slides in my series on PowerPoint Tactics, utilizing text effectively in your presentations is covered in more detail.