It notices things like rapid acceleration, hard braking, and speeding. It also notices if you are handling your phone, and in all of these conditions, provides real-time feedback, though the apps website did not exactly explain how it would do that (considering such a warning could be distracting in of itself).
Finally, the app helps employers and fleet mangers by altering its drivers to road hazards, and provides tips on safer and more efficient driving, which in turn reduces costs.
Driversiti says that it has the only patent for a phone crash-detection system, and will begin licensing the product starting next year on a commercial/fleet level. That could include car clubs, car manufacturers, or shipping/delivery companies.