Nobody said anything about performance/watt. It doesn't have to be more efficient. It only has to draw less power, most of the time. And most of the time you're staring at a computer screen, you're not asking it to do anything - you're reading, or thinking about what to type next. So idle power is the most relevant predictor of battery life for a mobile chipset. And ARM definitely has the advantage there.

As well as weighing less and being cheaper. So there's no call for laughing and crying.