I used my ereader for teaching two books this semester. A colleague also tried hers for the first time in the classroom.
I can say, I love my ereader, but I'm never going to use it in the classroom again. It's too hard to have a discussion and have to flip pages on the ereader. It's just not fast enough,compared to flipping through a physical book to look something up. That's what we both decided, independently.
So think about the usage: if you're going to need to refer to longer works, such as novels, from the ereader, in discussion settings, think about how often you might need to look up different parts of the text. But for something where that's not needed, such as an online class, it might work better.
I still love my ereader. It's just not great for discussion settings.