Statistically irrelevant no doubt, but even so, here are some photos taken within 30 seconds of each other of approximately the same scenes.
Round 1 - inside, quite close up
Top is Samsung, bottom is iPhone 4. I know which I think is better. The original images are available to examine by clicking on the images below.
Round 2 - Outside
We examined these photos "blind" (ie, we didn't know which image was taken by which phone). We mis-identfied which image was which. Overall, they're pretty similar but the windscreen of the silver car, 3rd back on the left, is better in the Samsung photo.