I've recently been using Variables as a great way to control the content on a few of our dashboards. The functionality has led to some incredibly well-layered graphics allowing hierarchical drilling on all visuals simultaneously - GREAT!
I have found only two drawbacks:
Firstly, variable options are not easily dynamic.
More importantly, though - I have no way to change the colour from the Default Domo Blue on the selectors to more Dashboard Pallette-appropriate colouring. I would absolutely love an option at some point in the creation or possibly in the "Edit Dashboard" → "Edit Content" → "Edit Configuration" pop-up window to be able to select the colour.