I have never been a big fan of noSQL precisely because of the lack of relational model, but I won’t say its not alluring. There still are reasons however not to jump to it, as this video explains:

Mongo DB Is Web Scale
by: gar1t

The very advantages of node can turn nightmare when implemented improperly. Take for example the non blocking function calls model. Its nothing new. This model has been used in a lot of languages, that were discarded for the serial routine. Erlang did it, VB6 did it. For a desktop application, its just fine, but for a webpage that renders once, the parallelization is not necessarily a good idea. Since any webpage is created by the server once and then, the server has no control over it, do we really need parallelization here?

Those who’ll quickly advocate node changes the page in realtime, let me remind you, js changes the page in realtime. Its still good ole client side javascript doing the changes. So, websockets do allow realtime communication, but they are still running as a different thread. You could just as easily write an application in PHP, and the websocket server in node and get the same result.