It's all free! All the features of KeePass and the Kee Plugin are available for free as Open Source Software. You are not going to be asked to pay a fee to unlock some feature you really want to use.

Works across all platforms. I use various versions of Windows, Linux, and OS-X. No mater what machine I go to all my passwords and logins are at my finger tips. Note you must run KeePass with Mono outside of Windows.

You have control of your password security. Not counting on a third party to store your passwords securely. I recommend saving your KeePass database to a small USB drive and attaching it to your key chain to have your passwords with you at every machine you work on. Keep a copy of KeePass Portable on the drive as well, and take advantage of Firefox Sync to sync the Kee Plugin to all your machines.

KeePass has a great password generator that supports various password requirements. Unfortunately the Kee Plugin does not fully support all options in the KeePass password generator, so occasionally I have to Alt-Tab from Firefox over to KeePass to generate a new password. Maybe Luckyrat in his spare time can expand the password generator support? :)