I actually like the concept behind the Idaho Stop Law as depicted here http://vimeo.com/4140910
However, the problem is that cyclists don't follow the rules of this law, at least in my observation. But beyond my personal observations, I've seen the misunderstanding of this law in numerous Reader's Comments section of various cycling-related news articles. Anyone that has read these comments have, undoubtedly seen the back-and-forths between cyclists and anti-cyclists. What I've noticed is that some anti-cyclist person will complain about some cyclist blowing through a stop sign causing them to stop suddenly, but the cyclist will defend this behaviour in the name of the Idaho Stop Law. Problem is, the cyclist should have stopped IAW the law.
Like I said, I like the concept behind the law and the above video does a really good job at illustrating the proper use of a bike with respect to this law, but just seems like many cyclists believe that they can roll thru a stop, regardless.