At the beginning of the computers driven craziness it was all easy - you could create your judgment basing only on one number. Speed of the CPU was the most important number in the computers, everybody were talking about kilo, mega and giga hertz.
In times, where memory was working at the same speed as CPU, and each tick of processor was one operation made it was easy to say: this computer can perform millions of operations per second - and in those times it was true.
Then everything got complicated, memory has stepped down and is always slower than the heart, some instructions required more ticks than other, but, still - hertz was a king. It was so important, that AMD was describing it's own processor with fake speeds, to corelate them with their main competitor - people were thinking that high frequency was the same as speed.
Even at this point, you were able to judge which computer is powerful, basing only on this one number - they were designed to perform numerical calculations and main unit speed was most important number of all.
Suddenly, new graphic era has started, new number has emerged - triangles drawn per second - are you a gamer or mathematician - choose a number for you. It was quite easy - all machines were working on the same operating system, on almost the same components and was using almost the same code.
They were "good ol' days" - now desktop computers has almost no meaning to game iindustry, there is a new leader and all magic numbers has been destroyed.
You cannot judge how fast is your mobile phone basing on its processor speed, it is meaningless. It does not matter how many cores it has, it has been observed that one version of Linux has troubles with four cores when other version of real time Linux is working flawlessly on only two cores. You cannot compare one device to another basing on processor, you don't have the same system everywhere - and even when it is the same system there is a skin, customization, different set of background processes and all these things will make your assumptions wrong.
What should we do now? "This device is up to twice as fast as the previous model." How to compare devices across manufacturers? We have to wait for some independent testing tools, some kind of mobile mark. When we cannot take any hardware number as a judging point, we have to create such number from pure calculation.