The idea of the extension is very good and I would say it is important to add it to any website that has a registration form. But unfortunately there are two problems:
1 - it's not working well with the extension _Sign Up Confirm Password
_ which only appear the strenght meter while typing in the confirmation field.
2 - (most important) The strength of the password seems to be measured by the number of digits and whether they are not repeated and not by whether it contains upper and lower case letters, numbers and special characters. So I used a bad password and it says it's strong. When using any password strength tool, they confirm that my password is very weak.