On the other hand I was on the interstate the other day and it told me to get off and take a detour, I ended up avoiding a massive backup. I don't always take the advice, but man I like having the opportunity.
I usually switch between Google Maps and Waze depending on where I'm going and how soon I want to get there. Google Maps if I'm in no hurry and want to take the "normal" way. Waze for if I'm trying to get there sooner (speed trap alerts and shortcuts help) and I'm either somewhat familar with the route or don't care about the stupid shortcuts. Waze has had me cut through neighborhoods and drive down gravel access roads to shave minutes off the travel time. Most of the time it pays off, sometimes you just end up wasting more time at intersections