There are other threads about this. I have a Sony 505, love the e-ink. Wouldn't swap it for the world. Battery life is staggering in terms of gadgets. Brilliant.
Only drawback is DRM. So look into that. If it isn't an issue then couldn't recommend it enough.
My eyes don't do well with long-term lit displays as they are just not like e-ink for the amount of reading I do. You can use your favourite lamp and of course, read outside in the brightest of conditions.
Get one!