Hi kiwidude,
For some reason this plugin downloads the "Details" cover instead of the "Front" one.
For example, if you look up the ISBN 9781593080778 you get to:
http://search.barnesandnoble.com/Ori...&pos=-1&ugrp=2 (or this one, ISBN: 9781593082079)
Click on the cover and it will open a new page with the "Details" cover selected, which is useless... but you can choose "Front" and then it will show a good cover.