WAZE, new (free) GPS app for smart phones

I just discovered this app for my iPhone and it seems pretty good although I've only looked at it a couple of days, but it's free. Basically it's a GPS that has a lot of high end features including voice guidence, but it uses information from other users to determine traffic jams and other problems. Both of these are reported and by using info that's based on the movement of users devices. It recommends other routes and since it isn't truck specific, you gotta make a judgement, but for free it seems like a good investment.