I know a friend that stalled his car pulling up to a traffic light. He nearly hit the car infront of him. Thankfully he unclipped with his left foot all the time and not his right. His left foot came off the clutch, but his right foot was still on the brake.
I will never forget my first ride going clipless. We rode about 25 miles crossing many streets. I was clipping in and out like I had been doing it all my life. I was so proud of myself for not falling. We stopped next to this cool little creek to rest for a moment. I unclipped left foot, put it down, was at a dead stop, but right foot still clipped in. For some stupid reason, I let go of the brakes and must have leaned a little right and I was a one-legged girl on a skateboard. It happened so fast and down I went bike and all into the creek! With hamburger knees and creek mud in my shoes, I had to get back on, clip in and ride the 10 miles remaining to our car. Lesson learned, hold on to the brakes when you have one foot clipped in!!
It's like learning to drive stick shift - you think you aren't going to stall, but you approach the intersection hoping the light stays green or a long yellow, and bang - it turns red, catches you like a deer in headlights, and down you go!!
Have been wearing them for a month - 3 falls bruises on both sides, and yes, with an audience each time. We'll get over it!!