From the Store description:
Password Hello manage your passwords use Windows Hello , use your Microsoft Account for Sync cross devices，we do not store your any of data include username and password, only use native Windows 10 API
This is ground-breaking, in a way. No database to manage and sync, just using Windows 10's built-in security features to store your third party passwords and the like. Which means that syncing is trivial and instant, through Microsoft's own servers and mechanisms. And it means that your Windows 10 authentication (e.g. PIN or iris recognition on the Lumia 950/Xl or fingerprint on the IDOL 4 Pro or Elite x3) system is integral, so no long database password to enter either:
As shown in the screenshots, usernames and passwords can be copied out via the system clipboard. There's no auto-fill or that kind of malarkey, but then I prefer keeping things semi-manual, so that my subconscious sees the passwords at least, giving me a fighting chance of actually remembering some of them, as a last resort.
The UI is kept super-simple, as are the fields available. The description can be much longer, I was glad to see, though I do wonder about the ultimate limits of this approach. Surely Microsoft won't want (e.g.) 100kb secure blobs of data syncing through its Windows Hello system for millions of users? Or maybe it does and this is one of the reasons for Windows Hello's existence?
You can grab Password Hello UWP here - it's free for the next five days as I write this) and then (in theory) goes up to a couple of pounds. Maybe(!)
Comments welcome if you start using this and hit any limits - I'd like to know what the limits are...