There have been more than a few threads on the board regarding 4S battery life being worse than the 4's battery life. The main changes to the system were the processor and the antenna. Personally I do not believe that an A5 processor at rest will draw all that much more juice than an A4...at least not a large enough difference to account for the huge differences that some people have been observing between the 4 and 4S Signal strength, however, can play a HUGE part as to how much power your phone sucks down. The iPhone 4 had a bad antenna due to its physical design. This design hasn't changed much in the 4S, so it stands to reason that they have boosted the transmitter strength on the phone itself since people seem to be reporting that they are getting better mobile connectivity. If this is true, then it would seem that reality has caught up with the iPhone in terms of the state of the art.