Not this FUD again!
It is true that MongoDB created a lot of unexpected problems for the early adopters who did not do enough due diligence and testing. I encountered them during my POC with Mongodb but I was able to get past them easily thanks to a robust user community. I have experiences no such issues with current version with Mongodb.
Today I am fighting my enterprise bureaucracy to get MOngoDB for our enterprise applications .FUD like this allows armchair architects to quote this article to spook the management and we are stuck with stuffing json as in a RDBMS tables.