Exceptions to every generalization
I edited this piece and challenged the authors not to fall back on easy generalizations. Some say ACID performance and NoSQL don't mix, for example, but that's not always true. Areospike, for instance, supports ultra-high-speed, ACID-compliant performance, yet it's a NoSQL database. That's just one example. You should also consider that NewSQL databases are, in fact, relational database management systems, but they're taking advantage of relatively new architectural attributes that weren't around when the well-known incumbent RDBMS were invented.
A few years from now when the NewSQL products start to get old, I wonder what we'll call them?