Apple's Keynote is the equal of Microsoft's PowerPoint and lets you create elegant, powerful presentations.
Clean design: As you'd expect, Keynote has a well-designed interface, with most tools a click or two away. Themes are wide-ranging and elegant, from simple black to leather-book.
Tailor your presentations: Keynote comes with a broad collection of predefined styles for paragraphs and shapes, for example, and you can change the look of objects and define your own styles.
Works across platforms: You can store Keynote presentations on iCloud, and you can edit and display presentations on OS X and iOS devices as well as Keynote for iCloud. Changes sync automatically across platforms.
Collaboration: You can easily send a copy of the presentation via email or share through iCloud. Through iCloud, you can work on slides with others, see edits, and add comments.
Transitions and animations: Keynote lets you create transitions between slides, animate objects on a slide, and use the Magic Move transition to have objects move from a beginning point on one slide to an ending point on the next.
Add media: You can add images and video to slides. You can also create a soundtrack for your presentation and record a voice narration.
Customizable presenter display: Move, resize, and customize objects on your presenter display to get just the right view you want.
Comparisons to PowerPoint: While Keynote is in most ways on equal footing with Microsoft's powerhouse presentation software, Keynote's lack of a native Windows version can be a disadvantage for those who work in a multiplatform environment.
Apple's Keynote is a powerful and elegant presentation app that can hold its own with Microsoft's PowerPoint. If you live in the Apple ecosystem, Keynote should be your go-to presentation app.