I had one of the original Nook tablets and have loved it! I moved to using the App because it is so convenient. If I have my phone or iPad with me, I always have a book with me. The only thing I wish it had was a way to connect to the Barnes and Noble site. That way I could look for books without moving between the Internet browser and the app. Overall, I have never had any issues with the app and all of my devices sync so that I can always find where I left off reading.
MEBS1969 about Barnes & Noble NOOK, v4.5.1