Hi chilady1,
I own a Sony PRS-505, a PRS-700 - and a PRS-600 at the moment.
The PRS-505 has been my first ebook reader and still is for me the best for just reading, as it has a great display. I love it and whenever I'm reading "just for fun" I use the PRS-505 exclusively.
As I also have to work on some books I sometimes need the possibility to make annotations in books while reading. Therefore I bought the PRS-700. I have been very disappointed about the screen and the way the annotation-function is working, but however, I had to use it. But it would never be a replacement for my PRS-505!
Then the PRS-600 came out and I thought and hoped it would be much, much better than the PRS-700 and I could sell the PRS-700 and keep the PRS-600. Therefore I ordered one. - Now I have it for about 10 days and I'm absolutely not happy with the PRS-600, even more disappointed than I was when the PRS-700 arrived.
The screen for me and for my eyes is only a little bit better than the screen of the PRS-700, the annotation-function is not at all working in the way I hoped it would and I'd needed it. I never liked the inbuilt light of the PRS-700, but it was my only chance to read with this device for more than for some minutes, as it helped me to deal with the glare/reflexion/contrast-issues. Now the PRS-600 doesn't have this light, but the screen is not that much better than the screen of the PRS-700 that I could use the device without such an inbuilt light.
Now I'm testing the PRS-600, but I'm quite sure that I will decide to re-sell the PRS-600 and keep the PRS-700 for the books I have to make annotations in.
Normally I'm taking both of the devices (PRS-505 and PRS-700) with me, as this also helps me to make sure that if one of them might cause a problem again, I'd still have a second one with me and wouldn't have to stop reading.
Somehow crazy, I'm aware of it!
I take care that all of the devices are "fed" with the same ebooks at any time so that I can switch between them without a problem.
Greetings from Germany,
Momo