There's possible value is calling out the genericness of getting to the empty form vs the specificness of the submitting the data on a single instance of the form. "Create user" takes you to a form that has potential to be any user (because it's empty), "Create this user" finalizes the action based on the filled-in data on the form.
If you click on a link or button called 'Create a User' that that takes yo to a form, it would be almost universally more usable to have the button at the end say 'Save' instead of 'Create this user'. Verbosity is not always a good thing on the web.
I'm probably in the minority but when I see "save", I assume it's "saving my progress". In a user creation form, even just "create" is clearer than "save".
But then we're back in "is it telling me to create the user again when I already clicked the other button on creating a user on the other page?" territory. I think we should use whatever feels right and A/B test the hell out of it, but spend more time actually solving more substantial problems that the copy on a submit button.
