Unfortunately Louis-René Auclair is overlooking a plethora of performance metrics. I mean he is a
marketing expert, not a GPU engineer, after all.

For example,
Fillrate:
iPhone 5S: 163 MPolygons/s
Xbox 360 : 500 MPolygons/s
iPhone 5S: 5.2 GT/s
Xbox 360 : 8 GT/s
Floating Point ops:
iPhone 5S: 76.8 GFLOPS @ 300MHz
Xbox 360 : 240 GFLOPS @ 500MHz (or 144 GFLOPS @ 300MHz, for comparison)
Honestly there's no comparison - take one step into forums that really dig into CPU and GPU performance - even anandtech - and you'll see. There may be a number or two that seem similar on paper, but in reality, you're saying a kid can lift a half-pound dumbell just about as good as an Olympic weightlifter.
I'm definitely not discounting the fact that iPhone GPUs have come along by leaps and bounds - but also note that we
are comparing 1-year old tech with almost 10-year tech.