- I always do my job talks with a presentation if I can. It keeps me organized, it avoids handouts and fiddling with overheads, and (with a remote) I can wander around more freely.
- I do the “math” part of methods with presentations; I can’t draw most Greek letters to save my life, and overheads are just too fiddly for me.
The big downsides are the lack of spontaneity, which affects all classes, and showing steps in figuring out a problem—the “here’s one I baked earlier” problem—that I think detracts from student learning in methods if you don’t structure the presentation right (usually I break from the presentation to work out problems on the board).
I couldn’t see using a presentation in a seminar; anything I’d write on the board in the seminar would be too hard to predict in advance anyway. But if I end up at a place with large introductory classes, I’ll probably use more presentations for the self-interested reason that “PowerPoint = good evaluations” and the more practical reason that I’ll probably end up teaching multiple sections of the introductory course at such a place anyway.
† Even when I use presentations, I normally don’t use PowerPoint, OpenOffice, or Keynote; instead, I use the über-secret slideshow features of PDF viewers like Adobe Reader or xpdf with LaTeX.