I would agree with others that Sony does not a very good job of displaying PDF as it is. However, if you are willing to invest some time to convert PDF into LRF (and I know it is a pretty big if for many people), the converted files are quite readable. Actually, my main use of PRS-505 is to read converted PDFs.
This thread is about how to convert PDF into LRF,
https://www.mobileread.com/forums/showthread.php?t=32360
And this post have some photos of converted PDFs shown on PRS-505.
https://www.mobileread.com/forums/sho...81&postcount=9
Good luck on your decision!