The iPhone 4 lasted around 30% longer in our GPU test compared to the iPhone 4S. This is actually a trend we have seen before, with the move to the 3GS we noted a similar impact on battery life compared to the previous iPhone 3G. If you're going to do any heavy 3D gaming, expect the iPhone 4S to burn through your battery quicker - although you will have a better experience on the 4S thanks to a smoother frame rate. Note that for sufficiently light 3D workloads (e.g. where the iPhone 4 is already bumping into Vsync), it's unlikely that you'll see much of a difference in battery life between the two phones. Citadel is simply too strenuous of a test for the 4. What really penalizes the 4S is its ability to run at nearly 2x the frame rate of the 4.