Kindle free book question?

So I recently got a kindle and was looking into downloading some of the free books that are available. I was reading a review of 'The Brothers Kamarazov' and it said the free version was extremely abridged, leaving out some of the most important passages of the book even. This review deeply concerned me because I do not want to be reading watered down versions of these books. So I was wondering: are a lot of the free kindle books like this?