From what I've seen, Great Whites normally don't attack like that. I've never been approached by a great white on my kayak out in the pacific but a few of my friends I kayak with have but they've never been attacked. One of my friends was attacked by a shark, it came out of the water like a missile and chomped down on the kayak's front end. The force was amazing. I was about 100 yards away when it happened. My friend got thrown off but he quickly climbed back on again just to get thrown off again. The shark was shaking the front of the kayak like nuts. In any case, that got everyone off the water in a hurry me included.
I think my friend got attacked because his kayak is blood red in color and he uses the mirage drive (mechanical pedals that look like flippers) that he operates with his feet.