I really prefer reading on an eInk screen, honestly. I use my iPhone for reading as well, but I vastly prefer the nook (of which I am a contented new owner) and the Sony PRS-500 I had before that. I am willing to suffer through a specific device for that comfort, though I agree with Nate that many folks might not feel it's worth it to them.
That said, anything that popularizes the digital book format is a net plus for eInk devices, in some ways. I'd own one if they cost twice as much, and at that price point I imagine there will always be someone selling them.