Security Considerations
This feature tightens the login security. However, if reCAPTCHA is enabled and the configuration is incorrect, you will not be able to log in and correct it. The only way to correct it is through the backdoor (for example, using COINSplus).
Also note that, as this solution relies on Google knowing about each environment domain you wish to secure, a Google email account is required. You should consider who will be the owner of this Google account and how it will be managed.
Lastly, Google does not actively publish the inner workings of their reCAPTCHA solution which would make it easier for people to create new ways to bypass it. That said, Google does use different metrics and/or data to determine the ‘interaction score’. If you are uncomfortable with this, then do not enable this feature.
Performance Considerations
There is a small overhead when the login page is loaded. A JavaScript script executes at the end of page load and requests a token from Google. This token is then sent back to Google when the page is submitted (that is, the user tries to log in) which then returns a score between 1.0 and 0 (where 1.0 is very likely good interaction and 0 is very likely a bot).