NodeJS allows you to solve a big problem called bottleneck, which is that each connection generates a thread that consumes 2MB of memory, how many more users, more servers will we need to support all these users.
NodeJS changes the way a connection is made to the server, instead of generating a new thread for each connection, each connection triggers an event execution within the Node engine process. Node claims that it will never stay in neutral, because blocking is not allowed and because it is not blocked directly for I / O calls.
Like most new Node technologies it is not easy to implement in existing accommodations. In shared hosting we will have to see if a node.js application can work; This will depend on the hosting company. If the hosting is in a VPS or dedicated server it will be easier since you can run NodeJS applications without problems.
In summary, NodeJS is good for its high speed, it has a very fast development, the applications to be so fast the user experience is better.