The aesthetic design of the iPhone 4 makes it really stand out from the competition. It is noticeably slimmer than the iPhone 3GS, measuring 9.3mm deep, whereas the iPhone 3GS’s is 12.3mm (that works out to be about 24% less). The iPhone 4 is slightly narrower too – 59mm to 62mm. The overall weight is the same – 136g – but the changes to the dimensions make the iPhone 3GS seem somewhat ‘bulky’ in comparison.