When Apple had released iOS 5.0.1, it claimed that bug causing the sppedy drainage of the battery in iPhone 4S would be fixed and the battery of iPhone 4S would have a longer life.
However, iOS 5.0.1 failed to fix the bug. Users still see the battery of iPhone 4S getting drained rapidly.
Instead, it seems that iOS 5.0.1has come with some bugs of its own.
One bug that has come to light is that iOS 5.0.1 will forget the name of your contact. When you receive a call or a text message from someone whose number is in your phone book, instead of his name you would see his number.
Given the fact that users are discussing this problems on various online forums, Apple must look into this problem, unless it wants it to become another “antennagate”.
Source: Cult Of Mac