Marco Arment wrote an excellent review of the new Nook Simple Touch and while he loves the Nook and its new touch screen, he still came to the following conclusion.
The Nook Simple Touch isn’t going to convert a lot of Kindle fans. Amazon’s ecosystem is going to keep a lot of people in.
My ideal e-reader would be the Nook hardware and interface, but backed by the Kindle’s ecosystem and services. It’s easier for Amazon to achieve Nook-like hardware design than for B&N to achieve a Kindle-like ecosystem, so it’s much more likely that the next Kindle will be a better fit than the current (or next) Nook.
Therein lies the major problem for competitors – Amazon’s store. Amazon.com has more selection and better prices than the competitors. Yes, there’s the DRM, but Amazon practically wrote the book on e-commerce. I don’t know the statistics for the e-book sales market share, but it seems like Amazon.com is the iTunes of e-books.