I also am part of several point-earning sites. I have no problem cashing out the points that I earned for Amazon or B&N gift cards. That makes that aspect of it that much cheaper. I love to review books (though I haven't in a while), which is another way to maintain my book addiction.
All in all, I'd say it was a good investment for me. I found the Nook on sale, refurbished, for significantly less than it would have been otherwise, even on ebay. I have a great way to earn credit for books and apps. Most importantly, though, for those that know me is that it's a GADGET! Now to go crawl back into my hole and play with my new toy..