Is MacKeeper a contoversial App that new Apple Users should be educated to stay away from?
It's certainly true that the app is controversial - search the Apple Discussions site for more on that - and while there were certainly issues with early versions current versions are reported better. 

However, there are many with very significant reservations about the sales tactics the company uses - pop-ups, paid-for recommendations on review sites etc - and that its uninstaller didn't work for many versions, so users kept getting further advertisements, allied with the  facts that the things the app claims to do are either a: unnecessary or b: can be done with free or cheaper alternatives means that the app undeniably has a bad name with many Mac users.

And again, for citation: search the Apple Discussions site for much, much more about this app.