The problem with the RIM is that while its physical design is nice, as is its OS, it has a pretty big flaw for the average user: it doesn't do email and calendar itself, only through a tethered Blackberry -- and not even then, if that Blackberry is on AT&T, yet. That's a pretty big function to leave out, at least compared to the nice native email apps on Honeycomb and iOS. Also its app store is in its infancy and they don't seem to be doing the right things to encourage developers to support their platform in addition to the two major ones.
I've tried a couple of scanned PDFs in ezPDF and didn't find them slow, but they weren't from google so perhaps they were lower resolution or something. Text PDFs and mixed text/graphics do work quite well though. I wonder if RepliGo is any better... but it costs $5
I also just picked up Quickoffice Pro HD but haven't tried its PDF reader too extensively yet. (It's too expensive if that's all you want it for though.)