It really isn't. Your goal should be to have no text, and never look away from your audience during a talk.

You can (and should) repeat key points, but every time you read, you lose your audience. And yes, you can have a little bit of text -- but since most people go too far in the other direction, it's best to aim to eliminate text entirely.

Slides should be simple graphical content to provide signposts and communicate things that otherwise cannot be expressed vocally.