An operational BI system should be focused on influencing the interaction with your customer to provide benefit to both the customer and your business. This differentiates operational BI from traditional BI. Traditional BI, like email, is often seen as a tool with a very fuzzy ROI, but hard to imagine doing business without it.

Measuring the benefits of operational BI is straightforward. If the process starts with a hypothesis (if a customer buys "A" they will be interested in "B"), you should build your measurement based on that hypothesis. By introducing the system, were you able to increase the sales of "B" to customers of "A"? Since presumably selling "B" has a monetary benefit, it lends itself to a fairly direct ROI as well.

It is easy to see the benefit from Operational BI because it directly addresses your business.