I took the course. I'd been riding since the mid 50s [half a century] and thought I knew what I was doing. I had the 'been there done that' attitude. I LEARNED A LOT! There were a lot of things I was doing wrong and, of course, a lot I didn't know or even thought was an issue. By the end of the course I had to face up to the fact that, even with all those years with motorcycles, I was a poor rider. I'm pushing 70 so my reaction time and motor skills are not all they might once have been. I feel that taking the basic course has been a great benifit in making up for the years.
My advice? Don't let anyone you care about ride a bike without them first doing the training.
By the way. I think this is the first thread, that I've witnessed, where everyone agreed with the first post. I wonder if everone would agree that even one beer can make a motorcyle a lot motre dangerous than it would if, instead, a car was being operated?