About the same to a little easier than a paper book, and about a million times better than any backlit screen. I too like the adjustable font size - I have mine set on the 4th largest, which is one up from the default but gives me two more as I age there are 6 font options.). On the K2 you can adjust the spacing between the lines - you can't do that on the DX but what you can do instead is specify how many words on a line - default, fewer, or fewest. I've played around with that for a few minutes and I thinh I like the fewer option, with a size 4 font. It's all personal preference, of course, based on what works best for you.
What I DON'T like is reading a novel on a backlit screen. It's fine to read off your Iphone if you're standing in line for Toy Story Mania, but more than about 15 or 20 minutes and my eyes start to blur. Same with a computer screen.
I can read for hours on the Kindle, though!!
