Hi Coral
The Kindle basically zooms out the PDF to fit exactly on the screen. PDF is intended for *exact* layouts, so doesn't work well when you want text to reflow to fit a different display.
Using
Calibre I was easily able to view PDF documents in AZW format without glaring formatting errors. I presume
Stanza will work as nicely.
Of course, the conversion's success may depend on the content of the PDF -- for instance, are the many images or graphics in it?