I just completed a class, and it was my first experience in a completely PowerPoint based lecture scenario. Sure, he jotted occasional notes on the board, but in about 50 hours of lecture I managed to only take about 15 pages of notes (including labnotes).
I see the use of PowerPoint as a pro since it gives profs the option of making them available to students, so if you're sick or miss a day then you're not scrambling to borrow notes from someone else.
But I actually think it's more of a con since my prof didn't really adhere to his slides, and by week 3 we were already 2 weeks behind. The end result was him giving us the slides and telling us to read them on our own. Gee, I could have stayed home and done that myself. So while it makes it easier for students to stay caught up, it just seems to make the profs less likely to stick to their material. Or, less likely to put as much effort into teaching it.
I'd rather handwrite notes off a chalkboard any day.