The number one thing I look for in software is a great design. I like to see an architecture based on every conceivable usage scenario. A good design encompassing all usage scenarios means that you don't have awkward navigation and clumbsy workarounds when important capabilities are requested by users after the initial product release.
I was not actually thinking about this very much when I went off looking for a better password manager than the clumsy text file I was using on a USB memory stick. The USB solution was good in that you could open the file and copy and paste logins and passwords, thereby defeating keystroke loggers and recorders.
But, the iPhone and the iPad do not have USB connectors (well... without going through an adapter that may or may not be available). So that was not very convenient.
So I tried out pwSafe, from a company called App77 -- http://app77.com/pwSafe/
At first, I did not get it at all; I was completely bewildered. There's a little user guide included, but I did not understand how I should set things up and why I should set them up that way. A couple of emails to tech support and I learned I could create a "Safe" and inside that Safe I could define "Groups" and inside those Groups I could define an entry with a login, password, url, email address, and extra notes and other details.
For example, you can have a Group called "Personal Info" and inside that group have all the login/passwords for various personal services, like your health care provider's website, or your personal Twitter information. Amazingly, with one push of a button, all of that could open up a website and log you into a website -- you don't have both typing or copying and pasting the login, the password, etc. If you want to share login/password information with others, such as a spouse, then you can define another Safe or multiple Safes,and provide the proper credentials to your spouse to gain access.
There's also multiple backup possibilities that are supported.
There is also an open source version of this at http://passwordsafe.sourceforge.net/
I would have to say that much as I like "Band of the Day" and "Lose It", this is now my favorite and most valuable app on my iProducts!