I've never used the Microsoft Book Search service, for no real reason other than I tend not to go near MSN search.
An article in last weeks NY Times claims that Microsoft is pulling out of its digitisation program, which was meant to rival Google Books and Google Scholar (MS has so far digitised 750,000 books and indexed 80 million journal articles). It also leaves a lot of libraries in the lurch who, rather than go with the Google model of restricting search results, had chosen to be in league with Microsoft, and the Internet Archive:
Microsoft’s decision also leaves the Internet Archive, the nonprofit digital archive that was paid by Microsoft to scan books, looking for new sources of support. Several major libraries said that they had chosen to work with the Internet Archive rather than with Google, because of restrictions Google placed on the use of the new digital files.Interesting times. Google marches forth, again. Back to the drawing board (begging tin) for some institutions.