That's my issue with phone reading. I can't just pick up any arbitrary pdf and read it comfortably, it has to be specially-formatted, or else you have to side-scroll and all that annoying stuff. And the pdf's I want to read are rarely formatted right.
You'll find that to be a big problem with any ebook reader except perhaps the kindle DX. I feel your pain though. I looked for months for an ideal ebook reader for academic papers, and concluded that such a product didn't yet exist.