Just purchased the iPhone 5C (White/32gb) from the AT&T store last night. Got it home and set up, when I felt something I hadn't in any of my previous iPhones (had a 3G and 4). Feels like something inside is loose. Whatever it is, it felt substantial (compared to the weight of the whole phone). I figure it is the battery.
I'm sitting in the Apple Store now waiting for a Genius Bar appointment to replace the phone with a "service part" (basically a new phone without the packaging as they've explained it). I know they're using adhesives to secure some of this stuff now, and also saw that some people experienced this with the iPhone 5 when it was released. I just wanted to reach out to see if anyone else has experienced this issue as yet. Hopefully it isn't widespread.