This add-on is phenomenal, and I consider it a must-have for using KeePass on a day-to-day basis. My one gripe is that, when going through the password change dialogue on websites, the ability to update the existing password entry seems to be limited to the fields found on the "change password" screen. That is to say, if there was no input field for the account's username on the screen, then the username will be erased from the entry in the database. In these circumstances, I simply open KeePass and update the entry manually.
The favicon-saving functionality also seems to be intermittent, but again, that is just a luxury feature.
Overall, the experience is wonderful and fluid!