[ricardobeat]

The main advantage would be performance, plus maintainability for complex UIs. Navigation can be nearly instant, since you're only making specific requests for data from the server, instead of shuffling html and reloading dozens of assets all the time.

There are trade-offs, of course: it is a tad more complex than the old way, but that is offset by simpler implementation in the server. Network round-trips are minimized, but you use a lot more memory and CPU on the client, and need more extensive testing. It's a great fit for webapps, not so much for more content-oriented websites.