Nookie books just ain't worth it.
In the time since I've set up a Nook sale, versus amazon, I've sold 1 book on the Nook site. 265 on the Amazon site. Now that's not a scientific study, and if I pushed it more with direct links to the site on Facebook (see previous posts on advertising on Facebook), maybe I would've gotten, I dunno, maybe 10. Point is there's a night and day difference.
1) Amazon was a HELLUVA lot easier to format the document to their specs. Nook has a manual process that almost allows you to either type in the document (like someone's gonna type 80,000 words on a web page) or upload a document, which is translated into a document to edit. The chapter breaks were all messed up, which I set up by simple page breaks.
2) Amazon has better marketing for self-published authors. The KDP Select program, which I dropped out of to get onto Nook, has some promotions opportunities to take advantage of like free giveaway days (5 per every 90 days) and a countdown promotion (the price of your book starts low and gradually increases, which seems a little backward, but whatever). The point is, when you're doing these promotions, Amazon is pushing it for you. How? Because...
3) Amazon is linked to by a ton of freebie sites. When you offer your book for free, hundreds (maybe thousands, I didn't count) are updated automatically for people looking for free good reads. That adds to your readership, which increases your chances of reviews, which increases your chances of more readers.
4) Amazon's reach is obvious versus Nook. Barnes & Noble should be commended for trying to stay in competition with Amazon, but with the Kindle Fire going gangbusters and the multiple Kindle offerings, Nook is on life-support, and someone's gonna pull the plug. You never want to see a monopoly form, and iBook from Mac still has a chance due to the popularity of Apple, but Nook just can't compete.
5) As the article linked above also mentioned, Amazon is much more global in reach. For me that's not as huge a deal, since my books both take place in America and are more or less American-centric, but I did have a huge amount of sales in the UK, as they are a great target audience for secular or atheistic post-apocalyptic stories like mine. And the freebies have sent my book to 8 different countries. That's exciting, if nothing else. Great to say my book is in 9 countries. (Not translated into 9 languages, though. That's BIG time.)
There's more, and I'd be happy to take questions based on my brief experience, of if self-published authors have other experiences, let me know.