It took 7 yrs for justice to be delivered. Today, we've to take a pledge that a similar incident does not happen again. We've seen how the convicts manipulated the law until recently. There are a lot of loopholes in our system, we need to improve the system.
Nirbhaya case showed us loopholes in legal system which four convicts took advantage of. Hopefully Nirbhaya will finally rest in peace as she got justice after long legal battle.
An example has been set today but it could have been done earlier. Now people know that they will be punished, you may extend the date but you will get punished.