<i>But this time, Wordnik got smart and tuned the application to account for the strengths and weaknesses of MongoDB (“Your app should be smarter than your database,” he says), and MongoDB to account for the strengths and weaknesses of the cloud.</i><p>That's my one major concern about Mongo DB. When I'm using a traditional database with a well normalized schema, my app doesn't have to be smarter than my database. My app can be pretty dumb, actually, and rely on the database to handle optimizing the way it stores data. Having the app concerned with the way data is stored violates the separation of concerns in my mind. The app should be dealing with transforming and performing logic on the data. Let the database deal with the messy details of how the data is actually stored.