Samsung promised that the new Galaxy S III would have twice the power and 20% less battery consumption than the previous Galaxy S II. GSM Arena has put the Galaxy S III through the paces, and it looks like Samsung kept it promise.
Galaxy S III : 10 hours and 20 minutes
Galaxy S II : 8 hours and 35 minutes
Galaxy S III : 5 hours and 17 minutes
Galaxy S II : 4 hours and 24 minutes
Galaxy S III : 10 hours and 1 minute
Galaxy S II : 8 hours