The biggest difference between password.ly and most other tools (including keepass), is that each password on password.ly is generated from your master password.
There is no database to lose, or not have access to if you're on another machine. It also has a command line client which works completely offline (though has sync if you're signed up and want to save sites/comments)
That is also a significant weakness, as revoking or changing passwords becomes very difficult.
Except that you should be changing the master password and other important passwords (e-mail, bank, Paypal, Mint) with some frequency. This scheme basically never allows for that to happen.
There's no official Android/iOS app. It feels like an unnecessary risk to use apps from different developers which can't easily be verified against their source.
There's no official app for anything except Windows. They're all open-source, though.
I think a web-based solution that is accessible from anywhere (incl. mobile) is pretty useful.
KeePass works on almost all mobile platforms, even those without web access, and KeePass isn't going to have downtime like password.ly.