This and the button style (which to me don't look enough like buttons to be 100% clearly identifiable) would be my criticisms as well. Other than that it looks nice.
I just looked at the demo again and it is only the <input type=… buttons that (since they have no extra styling compared to the other inputs?) don't stand out enough, when I imagine the <button type=… ones next to a form they look fine. (I personally like a 3D-effect on buttons, but that's really a matter of taste and doesn't always fit the other elements)