I missed the requirement to discuss the advantages and disadvantages of NoSQL db’s, so here is an Add-On:

The following article seems to sum up a lot of the situation:

http://www.hadoop360.com/blog/advantages-and-disadvantages-of-nosql-databases-what-you-should-k

Disadvantages of NoSQL databases

Advantages of NoSQL databases

My Take:

Personally, I think that the main thing is the concensus that SQL has. Even if people agreed 100% that NoSQL was the future, they still have no agreement on which implementation should be used. If I were to see a truly agreed upon SQL-less syntax for CRUD operations on a whole bunch of NoSQL DB platforms, then I might see more of a need to try and master that Syntax. Until then, its more conceptual, just learning things that might be out of date relatively soon.