As I do have books at the Nook and the Kindle, I downloaded the apps for my Android phone.
Nook by Barnes & Noble
It's not very intuitive for turning pages since I got use to using FBReader and iReader. It would be ideal if it used the Volume/Ringer Up and Down and the track ball to assist in turning the pages. I needed to swipe right to left turn to next page and the other way to go backwards. Tapping works but not consistently.
The formatting of the books are inconsistent. I opened one book where on some pages it was single spaced and other pages are double spaced. What's up with that. In another book, you see light line borders around the paragraphs. Not all links work. Not all books have chapter links.
You do get NOOK FOR ANDROID QUICK START GUIDE. I thought it might quickly tell me how to navigate around a book. It does not tell you anything. It's promotional thing.
This program needs a lot more work before I might use it.
Kindle by Amazon
The page turning controls are the same as the Nook. At least the problems I found with the Nook do not exist with Kindle for Android -- formatting and chapters links.
It's good that Amazon kept the functionality of Kindle for the PC, iPad and Android consistent.
Thumbs up for Amazon.
One of these days, I'll do a quick review of Borders ereader app. Hopefully, the program stays around as the store fronts are slowly disappearing.
Bottomline for me... I'll be converting my books to a consistent format using Calibre and find that one ereader app that I like. I'm still playing with the apps. It may be a different app depending on the platform -- pc, iPad, Android. It will not be Nook or Kindle as they don't like books from other sources.