There is a UI design flaw in the nook that's been bugging me ever since I bought one. It has been about 6 mothns of using it regularly (every day) and it still bugs me. So I thought I'd rant about it.
Given below is a picture of the nook showing a hand holding it in a typical use position. You will notice that the nook has two buttons on each side for turning pages. The bottom buttons on each side move the page forward. The top buttons move is backward.
I find this very counter-intuitive. Many computerized software and hardware have the equivalent of the back/forward buttons. The tasks may be different - back/forward page browsing on firefox or previous/next song in iTunes. However, one visual principle remains the same - left button is back, right button is forward.
The nook breaks this visual principle. Here, the top button is back and the bottom button is forward. This would not be half as bad if the buttons weren't marked with left and right arrows. This creates a mentally inconsistent model - top/bottom is mapped to left/right.
Even after six months, I haven't gotten used to it and often keep pressing the left bottom button to go back a page.
From another point of view, this design makes sense. As you will notice from the picture, in the typical use scenario, the thumb of the user rests on the bottom button. Since moving forward is the most common operation, it is provided at the most ergonomically convenient location.