In the past, when I were an English teacher, or anyway when I led English majors in language activity classes, and had no need of nor, often, any access to, ppt technology, what I knew of the device was what students would report sometimes when they had some higher faluting foreign lecturer than just the oral English dude. I would ask if they understood the foreigner, and they'd so no, but we could read the ppt. Thus, ppts seemed like (a) a way for students to not practice much English, but (b) a decent way to get class info across.
Well, that was then. These days, if the students ever did learn how to take notes, they've forgone them in favour of a phone picture of the ppt screen. That, I think, is what's getting me concerned about ppts. The ppts might end up being useful only if you can get the student to interact with the photo they took of your screen.
Which is... okay, I guess.