The new Microsoft sub-site is here. Worth bookmarking. It's really well done - part advert, part tutorial. OK, so even a mobile implementation of an OS is an insanely complicated entity and even this can only scratch the surface, but it gets the main advantages of Windows 10 Mobile over rather succinctly and with just the right blend of static images, animations and videos:
I've remarked before how there's easily enough in Windows 10 Mobile for me to recommend it as an update for most users of 8.1. Though not all. Article coming soon.... I promise!