It's a nice script, and a lot of effort has gone into it, but it's sad that it makes it hard to do what it is meant to do: insert citations from Google Books into Wikipedia. For instance,
* It works only from the overview page for the book, not from a certain page of the book
* Consequently, it does not automatically include the page number being referred to.
* It omits dq and q parameters from the URL, making you type them back manually if want them to be in the citation for highlighting
* It silently skips over many non-ASCII characters in author names etc., making it all but useless except for Western mostly English-language authors whose names come from a small alphabet.
* Minor problem: Despite being originally based on GPLed code, it's been changed to a different licence which makes it is a possible license violation. (Well, the code is all trivial, but…)
It would be great to see these issues fixed, but it appears that some of them may even be design.
Otherwise, a pleasure to use.