There is plenty of coverage online about challenges for the Nook ebook reader sold in the US by Barnes and Noble. The challenges are not limited to the Nook as there is a battle between device manufacturers for ‘ownership’ of the reader channel.
As tablet computers become lighter and have a longer battery life, readers will, I suspect, prefer a device that delivers a range of services and not just access to books, newspapers and magazines.
The ebook reader space is brutal, as Barnes and Noble is discovering. It would be interesting to see how the Kobo is going for Collins Booksellers.