I installed iOS7 for the first time this morning, and it's way too early for me to tell. The colour scheme is a bit jarring, but it's also very unfamiliar so time will tell how well I get used to it. Some of the setting and new functionality seem a bit odd or confusing, but no more so than I'd expect with a new interface. The huge configurability in the camera app was a bit of a surprise.
Right now I have absolutely no idea how much I like or dislike the new design. I've been able to do everything (very few things so far to be fair) I wanted to do, and encountered some small frustrations and nice surprises. I'll see how I feel in a week or two.
How long have you been using iOS 7 for?