With Stream you can check the activity on your website from the overall activity up into very detailed segments. Stream has helped me to solve a problem with massive brute force login attemps. With Stream you can filter these failed login events and get some statistical data about the extend of the attacks.
And if the number of attacks becomes overwhelming and clutters the activity log you can suppress recording failed attempts using a simple filter (see post How to prevent logging of unwanted actions).
What I'm missing sometimes is the possibility to select multiple items from the filter select lists.