Like Cristian, I like the idea but it's need to be refined.
The others « Wiki Loves XXX » (WLM, WLE, WLPA) are on Wikimedia Commons and are base on items lists (monument list, natural monument list and public art list).
Are you talking of a « importing books on Commons contest » (based on a list ?) or of a « proofreading contest » ?
By the way, we should absolutely re-do the « 10th anniversary proofreading contest » but obviously, we need a new name ;) and « Wiki Loves Books » doesn't seem very suitable to me.