I think it's more the "JS" and less the "Node". If you're building a web application, for the most part, Javascript is part of the equation, especially as frontend dev has shifted from "write a few lines of html" to "render an application".
From there, Node isn't that big -- it's a few libraries for interacting with the system. The assorted framework stacks and whatever haven't really sorted themselves out yet.
From a technical standpoint, what Node does well is that it's basically async-IO-by-default, which is very nice for real world performance, whereas in most-every other environment I've worked with async-IO feels like an unwieldy addon where example code is hard to come by.
From there, Node isn't that big -- it's a few libraries for interacting with the system. The assorted framework stacks and whatever haven't really sorted themselves out yet.
From a technical standpoint, what Node does well is that it's basically async-IO-by-default, which is very nice for real world performance, whereas in most-every other environment I've worked with async-IO feels like an unwieldy addon where example code is hard to come by.