I love me some Mongo hate

http://nyeggen.com/blog/2013/10/18/the-genius-and-folly-of-mongodb/

"Being able to walk with them doesn't change the fact that as of right now, MongoDB is clown shoes."

But seriously, the author makes a great point:

But actually, that's the Tao-like genius of MongoDB – having absolutely nothing new. Most databases are built with some killer idea: the consistency protocol for Cassandra, the crazy data structures of Redis, or the data-processing abilities of Hadoop. MongoDB has mmap, and by "has", I mean "uses" (but hey, posession is nine tenths of the law). Not having to design your own caching algorithms or write strategies, and using the simplest possible implementations of everything else, lets you get to market quickly and focus on marketing your benchmarks, consulting to bring your customers up to Web Scale, responding to haters, or learning about concurrency.