Let this be a warning. Kindle are actively removing any products that do not have original content. I have a lot of books on Kindle and most of my stuff is written by me, but they found one of my early ones called Twitter made easy and removed it yesterday.
I rewrote about 30% of it and added more content as well. Different cover also.
So be warned.
I think this good in the respect that quality content will now surface, but I am quite suprised how deep they are going.