Yep PDFs, especially ones with images or diagrams, aren't so hot on ereaders.
However I have gone for the cheapest ereader at the moment which is the Foxit eSlick. It only reads PDFs (and txt) but comes with software that lets you print any document to PDF. Still full A4 sized pages aren't good but I am happy to use a PDF editor and PaperCrop (free:
http://jupiter.kaist.ac.kr/~taesoo/p...index_eng.html) to get what I need from the eSlick.
Mainly cos I am holding out for a more expensive next gen A4 ish sized eReader, at the moment they don't cut it for me. So I brought the cheapest to last me a year or two before I upgrade... to something...