I used various S7 handsets in Samsung's booth at Mobile World Congress to shoot pictures of things I had in my bag, other people in the room and even the phones' hidden features. Double-tapping the home button to launch the camera app was a huge boon with my hands full of phones taking photos of phones.
The hardware and software are prefinal, so the photos are only indicators of camera performance; a final software update could always change things. And remember the conference room lighting? Samsung's booth was fairly bright, but I won't be able to get photos in other lighting conditions until the final review phone comes in.
Overall, the photos I took looked quite detailed. In some cases, I tried getting closer than the camera wanted, so it wouldn't macro focus using automatic mode. There's a new photo-sharing feature I really like, which lets you upload or email a pic right after you take it (you can turn this off, of course).
The front-facing flash might take some getting used to. The screen blinks over to bright white for a moment before the photo is taken. A selfie will take a bit longer to capture this way, and it's a little odd if you aren't expecting it. But it does offer another option for brightening up poorly lit selfie scenes.
Samsung continues to refine its native camera experience. I'm really looking forward to getting the S7 and S7 Edge out into the wild for even more photos.