Found a bug with coupon entry.
In the sidecart and checkout pages, add a coupon then remove it instantly. When I try to re-add the same coupon it won't allow me. The field is pre-populated which is good but nothing happens when 'Apply' is clicked. If I close and re-open the sidecart it makes no difference. The only way to re-apply the coupon code is to proceed from the sidecart to the checkout page and re-enter it there.
Tested in IE and Firefox.