Slides are meant to illustrate a point or hold the main points of a discussion. As such they are not intended to be written as text offering one or more prose paragraphs on the slide. If an audience sees an entire paragraph written in sentence form on a slide, it can be overwhelming. If the presenter then proceeds to simply stand at the screen and read the paragraph off the slide, one begins to wonder why the presenter is even there at all. Why not just mail me the handouts or an article. Think of the presentation as more of a conversation, and think of the slide as more of a floating illustration or reminder. Work hard to use your voice to be interesting and avoid reading the slide text out loud unless it is being done deliberately to emphasize a point or an aspect of the language. The reading pace and listening pace of the brain are often quite different, and having these two thing happen simultaneously can diminish the effectiveness of both of them.
Images can be valuable Stunning images are arguably the most powerful aspect of Powerpoint