I don't like how it gets in the way and that you can't avoid accidental presses of the button. (sammobile.com)
The device also allows you to disable the touchscreen to avoid accidental presses if you just want to use the page buttons. (blog.the-ebook-reader.com)
The physical buttons are stiff enough to prevent accidental presses, though perhaps a bit too stiff. (computershopper.com)