I found it quite aggravating, too. I tried to use it for several drives today, but I had to repeatedly disengage it. At one point, the route on the screen had me going straight through an intersection, but the car planted itself in the right-turn lane, then was moving inconsistently as it reached the intersection, as if it couldn't decide whether to turn right or try to change lanes with no space left to do so. I disengaged and got an immediate FCW alert because of a car that was turning left in front of me. It frequently took turns too rapidly or too slowly, put itself in the wrong lane or couldn't decide which lane to be in, etc.
I don't plan to opt out, but right now, IMHO, the software is downright dangerous. People really should not be too eager to get it. As I've posted elsewhere, this is not the finished product for which we've paid thousands of dollars. Even calling it "beta" software is quite a stretch.