We constantly monitor how accurate our predictions are, and try to adjust accordingly. We'll have a blog post soon that explains more about how it works.

As for competing with looking at NOAA radar images, try a little experiment: Next time rain is headed your way, look at a radar animation and try to quantify when the rain will start. The fact that I'm completely unable to do that (even while looking at the damn radar animation) with any accuracy is the reason I started building this app.