I’m just starting out my exploration of this technology. There are >50 NoSQL database offerings, and they each seem to be targeting specific use cases. I don’t think there is a single one-size-fits-all “NoSQL” technology; they all seem to deliver performance by relaxing the relational model in slightly different ways. If you need a general, flexible solution and you don’t have petabytes of data, traditional RDBMS may be for you, and scalability is your trade-off.
But if you really need the scalability, then it is imperative to pick the NoSQL solution that most closely mirrors your expected use case.