It allows loading pages without refreshing browser window. User will not notice any loading indicator/progress, pages will instantly "replace" each other.
> User will not notice any loading indicator/progress, pages will instantly "replace" each other
Um, no. The pages won't "instantly" load - the browser still has to make a round trip to load the page content.
A loading or progress indicator should still be shown letting the user know that this round trip is taking place - especially important if you're on a slow US cell network. If a user is on a slow connection and no visual feedback is given they may end up mashing a link, making the load time worse - or, worse yet, assume the site is broken.
