I agree that I'm seeing a lot more graphically pleasing and entertaining slides at conferences, and I think those are more impactful than ones that are full of boring text and charts.
But I still think too many presenters use PowerPoint as a crutch. The best presentations are the ones where the presenter adds a ton of context over and above what's on the slide - tells stories, weaves a narrative, gives people something to remember. I've always thought that the mark of a good slide deck is that if someone who didn't attend your session looked at it afterwards and couldn't possibly figure it out (some think the opposite is true!). If you pack your slides so full of data and info, then why do people need to pay attention to the speaker? The slides should merely be a visual add and a cue for the speaker.
I think it would be interesting for more conferences to do a Pecha Kucha format (20 slides / 20 seconds per slide) and leave more time for Q&A. Would be neat to see if the audience felt more or less engaged after this type of presentation (or more informed).
Great discussion going here!