Often, presenters get stuck on page 1. The long list of bullet points which are supposed to summarize the story becomes speaker notes to deliver the entire presentation verbally without the visuals.
Well, that is great right? A captivating story standing on its own with out the need for slides. Things are usually not that perfect. Instead of a captivating story, the presenters reads out the summary bullets, adds some "uhms", hints a bit at the key points but stays at a generic level, saying that the real story will follow. After 15 minutes, the actual presentation starts, which the audience has already heard, more or less. And then, when the presenter reaches the final summary slide, the whole things gets repeated again in 10 minutes.
When presenting live, it is best to consider your first slide a teaser slide, not a summary slide. Hint at what is about to come, but resist the temptation to spend too much time on it. Instead, run the presentation using the visuals.
For presentation documents that are meant for reading a summery page is appropriate (not a teaser page), and in that case I would actually add more text in a smaller font for someone to get the full essence of a story in 1 page, just in case she does not click through to the end.