Kindle Review has a review of the features of both the Nook and Kindle WiFi-only ereaders. Even though the title of the blog is “Kindle Review” the comparison is unbiased and anyone who is considering either unit should take a look.
Overall, the blog prefers the Kindle, but with the following caveat: The two critical weaknesses of the Kindle WiFi are its lack of support for Library eBooks and its lack of ePub support. The missing MicroSD card and not having the fancy helper touchscreen hurts a bit too. If any of these are deal breakers for you then the Nook WiFi would be a better choice.
