Any iphone user would be afriad of their phone looking like the one in the photo below. So many people own the Iphone, yet is it really a safe phone to have? no. Being an owner myself i will admit, i love this little piece to technology. Although it is very fun and helpful, it is not durable.
Iphone 4 varies from the 3G and 3GS because the iphone 4 has both a front and back screen composed of only glass, whereas the front of the iphone 3 is glass front. When remaking the iphone design for the 4, Apple decided a scratch reistant screen was important, so in doing so they found a harder material. This harder glass is scratch resistant, but here lies the major problem. The harder material allows much less flexability when the phone is droped. Flexiability of the screen is what would save the phone when dropped. Because it lacks flexiablity the stress of the force on the glass upon collision with the ground causes it to not bend, but shatter.
Another main reason the iphone is so prone to a shattered screen is that the glass screen hangs over the edge of the phone, so when it is dropped every bit of force is put on that one spot of the glass. The iphone 3 had a metal ring around it which protected the glass. Becuase the glass hangs over the edge of the phone the glass it what recives the impact of the fall.
The Iphone 4 is so likely to shatter when dropped because all the momentum gained when it is dropped is let out on a hard, nonflexable material. The force the phone hits the ground with is too much for the glass to handle, and shatters. So with this said, all iphone users need to be careful with their phones, for even a very small drop can cause a ruined phone. Times like this when i wish Newtons laws were not true. Gravity is a serial killer of iphones. Beware.