One big usability breaker is the well-known fact that the “Autofill Password” option on iOS keyboards does not show all of the time. For me at least, this happens very regularly.
The current workflow then is to minimize the current app, open bitwarden, search for the correct login item, copy the relevant data manually, pasting it into the app.
However, when you long press on an input field in iOS you get an option to autofill on demand. Strangely, it seems Bitwarden does not take over that Autofill->Password option and it keeps opening up Keychain Passwords.
Here is a video of what a new workflow could look like, if Bitwarden ever got to also taking over the Autofill->Password on-demand option:
Note how it doesn’t work flawlessly using Keychain Passwords either.