I've had a Nokia Lumia 520 for a little over a month now and thought I'd share some opinions on it.
The OS itself is very nice for my impaired eyesight. (Probably mentioned it before here, but I'm totally blind in my left eye and legally blind in the other.) Big fonts, big keyboard, and generally just a lot of big text. Not crazy big, but big enough to make it enjoyable to use further away from your face compared to most phones.
The screen is pretty good too. Much brighter than my MacBook Pro's screen even. The whites look great, and you get a really nice vivid color.
I'm using Freda+ as my choice of ebook reader app. The customization is great. You can do it right to the RGB numbers, aswell as set the margins and line spacing. The best part is that you can save all your settings as different presets and change to them very easily within the book you're currently reading.
Works with Dropbox, SkyDrive (what I'm using), and Calibre.
My screenshots don't do it any justice.
But anyway, I'm enjoying it and thought I'd pass it on.