Keynote is very nice, it's true. It makes it simple to get really pretty results, and the ability to just drag-n-drop pdf files into your presentation is priceless for scientists, who typically have to go through obscene contortions to get equations from LaTeX into PowerPoint without converting them to fugly rasterized messes.

One trick Keynote could learn from PPT is the way PPT automatically scales down the fonts on a slide if it starts getting crowded. I really missed that when working on my last presentation.