There are a bunch of before-and-after shots here between apps on iOS 6 and 7.
I’ll grant that (1) I use almost none of these apps. And (2) people always instinctually prefer the familiar, at least at first.
That said, it strikes me that in only a handful of cases is the iOS 7 version an improvement; in many cases it’s a push; in a solid minority (Instapaper, Hipmunk, Days to Go, etc.) it’s a downgrade in visual presentation.