I like 1 Password a lot. There are several features that I really like, but here are a few reasons why I decided to use 1Password after trying a few different apps. I opted for 1Password Pro because it's a universal app.
I REALLY like the fact that you have a lot of control over how secure or quick and convenient the passwords are. First, there is a master passcode to open the app. Then once you are in you can set up the information to be accessible once you've entered the app. However if you have some really important information you can Add another layer of protection so that even if someone opened the app their is another layer to get through.
I know, why have to remember or enter more than one password for an app that saves you from remembering passwords. Well in my opinion it's a nice feature because you might have one group, such as forums and places without financial information, and then another group for accounts linked to payment processes. The extra level of protection can be added to just the data worth taking the extra step of precaution.
The app can be linked to dropbox and then you can sync your devices. I use this feature because I always have my phone and sometimes don't have my iPad (althouh it's a rare occasion when the iPad isn't latched on to me.)
Many users seem to like the automatic site log in feature that's included in the browser also. You can backup and restore the app with a Windows, Mac, or Linux computer. If you have a Mac, there's a desktop version of the software that will keep things organized and in sync, although I haven't used it and can't give much information in that particular feature.