Is Google Books a reliable source of BiBTeX records? I've found a negative feedback back from 2008, and not sure it is sill valid. Unlike Lead2Amazon and Tungare's ISBN to BibTeX converter, Google Books relatively well understands Unicode and replaces it with control sequences. But are there factual errors in records?
The site you linked critizised Google books for 5 issues. I tried some of my books to verify which ones are still valid:
- multiple creator and/or translator: one test case only, translator was exported as author
- clipping title: works for me
- names of some publishing houses: works for me
- publishing place: no publishing place is exported
- ISBN: works for me
I use the information from Google books from time to time and so far, I have not come across books where information was given, but it was plain wrong. I cannot say whether Google books is better or worse, more or less complete than other sources. If you have doubts about the reliability, there are plenty of alternatives in the question you linked to, maybe you should do a comparison yourself.
My suggestion would be to use a tool like Citavi, Citeulike, Zotero or Bibsonomy to transfer bibliographic information from websites to your bibliographic database, because even if you export from Google books, you would have to add the information to your database in some way.