I downloaded it earlier onto my phone and iPad. Still exploring, but so far one of the most important features is in the Passwords section of “Settings.” Now it first lists every website or app on which you have a password that has been identified as having been included in a security breach, and it gives you a handy link right there to change it. Next, it lists passwords, and their associated sites/apps, that have been reused on multiple services, and lists those uses so that you can reduce how widely that password is used. And finally, it lists all of your apps and sites as it did in the past, with the login information for each.
It’s a great (though sobering - I had over 100 items that had issues) summary in one spot of your password usage, and associated vulnerabilities.