Loved the idea of this. I have just tried to import my list from LibraryThing where I have 695 books recorded.
Whichever export I use - xls or csv - I get the message "UnicodeDecodeError:'utf8' codec can't decode byte )xff in position 0: invalid start byte.
The files open in excel, and I have saved them again as csv but it does not help.
Sad that the add-on does not support this great cataloguing site. Goodreads which is supported seems more of a social network site than a catalogue.