The main image obviously grabs your attention, especially when you're driving. The cracked windshield and splattered blood send the message of a car crash. Then you read the print at the bottom saying, "GET THE MESSAGE. TEXTING WHILE DRIVING IS A DEADLY DISTRACTION."
I can appreciate this billboard for many reasons. One is because it sends a great message and targets many audiences (anyone who texts on a cell phone). Another reason is because the image, text, slogan, and layout make a great advertisement. It has a large image that immediately grabs your attention. Your eyes see the "OMG" and connect it to the message at the bottom. I think using the text version of "Oh my God" is a great way to pull the ad together. The overall visual creates an appealing advertisement, which can be used on a larger scale billboard, and send a needed message.