Create custom audience groups and then show targeted notifications to them e.g. Users who have came through Google search can be a group and all users who have visited your site multiple times can be another group.
Launch notifications with in seconds of installing JS on your site. It takes a simple click to turn them on/off. Also, you can run multiple notifications at the same time - one for each audience group.
You can change look and feel of the running notifications almost instantly by simply going to dashboard and click on few links.