More on Google Scholar

It turns out Google Scholar is also pretty good in German. It is almost as good getting full text journal articles, scholarly dissertations, government reports and whole books in German as it is in Russian. So why is it so lousy in getting any PDF files containing full text documents in English? Also can anybody tell me how good Google scholar is in other languages? How is it in Arabic, Turkish, Korean, Japanese, Chinese, Spanish, French and other languages? Does it bring up a lot of useful full text PDFs in these languages like it does in Russian and German or does it draw a blank like it does in English?