I'm indifferent to the changes of the GCD on the UI. Doesn't affect me in the least. It is bright, but I think it helps me notice when my GCD is up, even when not staring directly at the bars. Lots of QQ on the forum though...
EDIT: Reading one of the above posts, I agree that an opacity slider for the GCD pulse may be a good way to go. Will get rid of the whining of a VERY vocal minority and will give more customization to the UI, which IMO is sorely needed.