The 700 is very good at displaying pdf files. Fast and supporting reflow for the text pdf's that are made that way, while for the rest horizontal half page reading works nicely with zoom in for pictures, diagrams...
Only double page scans are tricky as well as double column text pdf's that do not reflow.
I have a 100MB pdf scan that I never imagined I could read on something less powerful/smaller than a tablet and it works like a charm on the 700 in horizontal half page mode and even Google books work decently - only the pictures/graphics do not sometimes, but that's an ADE bug since they do not work in ADE on my PC either, only in the regular Adobe Reader
If you have a Borders/Sony Style close where they have the 700 demo, load some pdf's on a sd card and go check it since the store people usually allow it.