Funny to see that almost 40% were most impressed by Button. I mean, I really like that guy (unlike Hamilton) and wish him all the best, but driving away from pole to an unassailed victory in the fastest car is really not all that impressive to me. It was a solid drive, not more. (I seem to remember saying the exact same thing about Hamilton after one of his wins in 2008... Can't remember which race it was, though.)
Hamilton on the other hand clearly overperformed. Partly due to luck, partly due to good strategy and partly because he kept his cool and the car out of trouble. He definitely had a harder time than Button and made the best out of what he had. I wouldn't exactly call that "impressive", but many other drivers out there apparantly weren't capable of pulling that off.
Personally, I was most impressed by Buemi, because, like others, I expected more of a Piquet style race from him. Plus, ist was his first race, he's only 20 and all that. So, definitely Buemi impressed me the most.