FaceID shows the difference between Apple and other smartphone manufacturers. Apple doesn't release features until they are absolutely sure they can engineer them to work perfectly.
As to banks, I'm fairly sure (although I have no inside knowledge) that the banks won't have been allowed to review this technology in advance of the release, so they have no real assurance here.
You can of course assume it's secure and as usuable as TouchID, but I'm guessing the devil will be in the detail on this one.