I use both phones in parallel during the trip to Crimea, Ukraine, and even took some comparative shots.
Only XT720 photos
Notice in the left side of the photos below, this is my finger. Happens to often with XT720, due to placement of the camera on the very edge of the phone, too close to the point, where you naturally keep your fingers.
Using flash in the poorly lit museum, during daytime. No nighttime pics yet.
Motorola XT720 on the left, Samsung Omnia i8910 on the right
My overall verdict stays the same, photo quality of XT720 is quite average, hopefully this will change in the next firmwares.