The two most oft-quoted advantages are:
- JavaScript is both server-side and client-side. There are fewer things to learn, less context switching, and the ability to reuse code across the two sides.
- Uses non-blocking I/O, and Chrome's V8 engine, to provide fast, highly scalable servers.
For me though, the most interesting part is the amount of activity happening in this area. There are a lot of very interesting ideas under development for node - be sure to check out the list of Node.js modules.
