For PDF, iBooks is very good and it's free!
I just noticed this thread - shows the benefit of having a good and descriptive thread title to attract readers.
I've been having a similar problem, but a rather more specific one concerning emailing PDF files using the GoodReader app.
I started a thread here, and twerppoet has been very helpful with his suggestions. It may help you too.
Hi All, Am frustrated with Mail and PDF files. I have been opening PDF files by holding my finger on the displayed PDF file in the body of the e-mail. This should bring up a screen with save options etc. However now when I hold my finger on the document a magnifying glass displays and I cannot open the file. Then I tried to open a PDF file which had a pdf dialog box displayed at the bottom of the e-mail. Now I have a grey coloured screen and cannot access my mail. What is going on???? Help!