Very Useful
I use Keys to keep all my auto generated passwords be it web login or mobile app login. So I only need to remember one master password. It syncs with the OS X version vice versa. I just need to enable icloud keychain on the OS X so it automatically logs me in on web apps. On IOS device, I use it to login mobile app. This helps me for not having my master password scattered on several webs or mobile apps but use it only as true master password.