Well, what I would say that article rewriter can't give the quality, in terms of readability. So, you can use these articles for submitting to article directories but you can't use on your site if your site is good then it would lose its importance if you use such articles, also, if you are posting these articles on top article directories like goarticle, articlesbase then it is hard to get approved.
So how do you use it and what is the main benefit of such tools?