Over all I have been very happy with durability of Motorola phones. I have never ruined a phone yet by mishandling. I have had a phone since 1992, and never been rough of them, but with the smartphone you tend to use them in more places and subject them to more possibilities for damage. In the 18 months I had my Original Driod it suffered three significant drops on to concrete. There was no damage to the phone until the third drop where the focus on the camera stopped working.
A couple weeks ago I was a MLB playoff game and attempting to TWI (text while (very) intoxicated). My Bonic took two hard drops on to the concrete About 8-9 feet. (No protection) With the exception of a few small pin sized scuffs on the battery cover there is no damage to the phone. Very impressive.
Fast forward to this weekend. I was at a NFL game with a friend this weekend. My friend let a guy next to him look at some scores on his HTC phone. The phone was in fairly solid looking protective case at the time. The guy dropped the phone about 2-3 feet on to the concrete and the screen shattered.
I realize there are other unknown variables such as the where the point of impact was to cause the glass to shatter.
I play poker in a place where I see about 100-150 people of a regular basis with all types of smart phones. For the most part most of the phones with broken screens are HTCs, iPhones and a few Samsungs. I have only seen one Motorola with a broken screen. After talking to the guy with the Droid with the broken screen I found out that he was a coach of a kids soccer team and the phone got walked on by a kid on cleats on the sideline.