Small UI note - when you focus the text box the hint text should go away. I found myself trying to select and delete the hint text since it wasn't going away by itself.
Well, yes and no. It's the default behaviour, but it seems strange as the text is centred. I think if you left-align the text box input, it would seem more intuitive.
Maybe I'm more used to sites implementing it with Javascript. It does seem to be the default behavior; I'm trying to figure out why intuitively I expected it to be different.