I read a fuckton of papers and non-fiction literature with images. ePub simply isn't useable in these cases. If I'm reading something with no images or graphs or anything, then fine. I'll use ePub, otherwise, no.
It does, actually. No ePub I've seen places the images in between text in a satisfying way. PDF's are designed in a certain layout to account for images and keep that design no matter what I'm viewing it on.
Looking for specific complaints, please