Originally Posted by afv011
And therein lies the problem, most PDFs are formatted for A4 or Letter, and being non-reflowable format, PDFs don't display well on 6" (and though OK, not great on 10" either), and hence make for a poor reading experience. The "bashing" you refer too is not for the format per-se, but how it renders on small screen readers.
I've read a lot of PDF textbooks on my iPad, swapped an iPad 3 to an iPad Mini. There's no doubt that the retina screen displays text a lot sharper, but I'm not finding any problems reading the same books on the smaller screen. Of course it would be nice to use the ePub versions of my books but I can't stand iBooks. For PDF reading I'm using ReaddleDocs, it's got a page crop feature that's really useful on the Mini to get the text to display just that little bit larger.
PDFs follow that old school of thought that content must look the same everywhere, something that is at odds with how they are used now. Problem is they have a lot of useful features; annotations that are stored in the file being the key one. We need a new format; PDFX say, with everything that current PDFs have but resolution independent.