The best thing to have it for is to collect data from fuel, timing, boost, lambda, wg duty cycle and much more. Plus it will allow you to graph and see the comparison of actual and specified...and read and clear error codes. If not into knowing what is going on with it...pass on owning one for yourself...and just try hooking up with someone that does own one if you feel you need it at some point.
But it is nice to change other functions...which lights you want as running lights, whether to keep fogs on during high beam operation, allow windows up and down with the key FOB, and more.