My group developed the latest, fastest NoSQL system on the scene (http://hyperdex.org), one that provides ACID transactions as well as a ton of other exciting features like scalability, consistency and fault-tolerance.

Yet when someone asks this question, I usually respond with "try a traditional RDBMS first."

The simple reason for this is that there is additional, implicit information in the question: the fact that someone is asking it indicates that they are not up-to-date on one of the most exciting revolutions taking place in data management. Such users will require extensive hand-holding, and there are a lot of SQL-related resources out there that can help them with this.

But there is a twist: what people are doing is kind of like how some religions have to turn you away before you become a true convert. Will an RDBMS user be completely happy? Perhaps, but if the application is at all demanding, they will wake up in the middle of the night because of a wedged DB, running out of internal table space. Or have to frantically hire DBAs to "optimize" their queries. Or hand money hand over fist to Oracle. Or discover that an AWK script is faster than their multi-million dollar RDBMS installation.

So it's not like people are turning you away from NoSQL altogether -- you will end up with a NoSQL system eventually, they're just making sure that you do this for the right reasons.