The nook will read ePub books purchased from any store that supports Adobe DRM. The nook will also read eReader books purchased from the eReader store (and I believe fictionwise as well).
I have a nook and it's a nice device, but I have to admit that I like my new Sony 650 better.
The nook does have the advantages of wi-fi, being able to read books from Barnes and Noble, and in the U.S. it's significantly cheaper.
But personally, I like the interface of the Sony better. For me, a dictionary is an important feature of a reader and unfortunately I find the way the nook has implemented the dictionary to be very clunky. Sony's dictionary interface is much better! Also the Sony is quite a bit smaller/lighter than the nook--making it easier to carry in my purse.
I'm planning on keeping my nook and will still use it. But my Sony 650 is definitely going to be my main reader.
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