What is this NoSQL?

Day by day NoSQL databases are releasing their new versions of their databases. But my favourite MongoDB has forgotten its purpose. And day by day then I find a limitation of NoSQL databases. Somehow NoSQL is not for everything. But in this way it seems like, it is not good for anything. I mean the MongoDB. Today I was reading about Security issues of MongoDB. But I couldn't find a problem with MongoDB. Because all those problems will come if we are going to use dynamic like queries or string JSON parsers.
I'm in a kind of a disappointment about NoSQL databases.