What's nice is that you can leave the OBD-II adapter plugged in all the time (as long as you don't have one of Flo's "Snapshot" devices plugged in there!). The app is on your phone (or tablet, or both) so you always have the OBD-II tool with you.
Torque Pro is an amazingly well done app. I had to clean a valve on my daughter's car and the procedure explained that the process would activate the check engine light. Didn't have to dig out my old OBD-II tool, could clear the fault code with my Android phone.
One nice feature of Torque Pro is the ability to set alarms when sensors detect a problem since it's always reading the sensors. I.e. you can set an alarm (talking) if the vehicle is overheating.