Wow, thanks for the very speedy reply, omk3! Much appreciated.
I had a feeling the screen might be okay, and that it was just a bit different to what I was expecting, so am relieved to hear that my experience is normal. I will experiment with different lighting conditions/booklights etc and see how I get on.
Other than that, I do like the PRS-505. I love my gadgets and as an author of ebooks, I thought it was about time I got myself some proper kit to read them on.
Thanks again.