Get a kindle. The e ink screen is far better for reading, and the battery life is amazing.
Better for reading outdoors, or in bright sunlight. Not necessarily better for reading.
Indoors on a duller day, or at night, the Kindle screen is very low contrast. Grey text on a grey background, and it's noticeably lower resolution than the iPad.
iPad is just not a good reader - too heavy and backlit screen (even Retina) is hard on the eyes. E-ink looks just like paper. Really no substitute if you are a heavy reader.
E-ink looks like newsprint at best. It's nothing like the quality of even a cheap paperback book, the page is so dull. (I had a Kindle 4 and have used friends Kindles of various generations)
And the new iPad screen is not bright at all. The minimum brightness on the new one is 3.28cd/m², which is roughly 1/3 the brightness of the previous model. If you don't know, that is equivalent to the brightness of three candles, dimmer than almost any reading light. And you can go dimmer still if you use the sepia tone or night mode.
There have been numerous studies that have shown that reading on modern high density LCDs does not cause any more eyestrain than paper, and in some cases are actually
better.
Ultimately, it's about whether you:
- Want a smaller & cheaper device you're more comfortable carrying around.
- Want a device to read outdoors or in bright sunlight.
- Don't want to be charging your device on a daily basis.
If you primarily read indoors and especially at night, the iPad 3 is a better reading device in my opinion. Text looks much better than it does on the Kindle, and there is no eyestrain if you set brightness to an appropriate level for the room lighting.
And while the Kindle battery life is supposedly amazing, I found that when I was actively using it (when it was new) it was lucky to last me a week, and that's without the lighted cover. Once I got my new iPad and started reading books on it, every time I'd pick up the Kindle it would tell me it needed chargingwhen you're not using it, the battery doesn't seem to last all that long.
I used to have the Kindle 4 but found it a pain in the rear to use due to the keyboard. It takes forever typing in anything. I sold it and bought a Kindle Touch which I'm really happy with, but even with non Touch I would prefer the original one with a keyboard (even if slightly larger) to the Kindle 4. Everything else was fine, but the keyboard drove me nuts.
I rarely ever found the need to type on mine, as I purchased books via the website, and I
much preferred having the smaller device and physical buttons compared to the touch.