Only thing I would add is that I personally find it a little frustrating reading them as PDFs due to the amount of scrolling needed (especially since I read them pretty zoomed in). But that's a really, really, really small complaint for an otherwise fantastic product.
My problem is that monitors these days are all widescreen, so my new monitor isn't as tall as my old one and so I can't fit as much of a page onto the screen, at least not at full size. On my laptop, I can just turn it on its side and rotate the page so that the screen shape fits the image better.