NoSQL vs. RDBMS: Let the flames begin! – stu.mp
"I guess what I’m saying is that my decision to use NoSQL, and I’m guessing others’ decisions to do so, has less to do with the fact that we can’t squeeze a few thousand writes a second out of MySQL and more to do with management and cost overhead. NoSQL solutions allow us to serve absurd amounts of data for a really, really low price. I’m happy to put my $/write, $/read, and $/GB numbers for my NoSQL setup against anyone’s RDBMS numbers.
We’re not nearly as dumb as everyone thinks we are; I promise."