This new generation hasn't made the huge leap that was made from the ps2/gamecube/original xbox generation to the ps3/360 generation and to be honest early games on new formats being compared to fully optimised games on outgoing formats is an unfair comparison.
I remember comparing original xbox games to early ps3 multiformat games and there wasn't a huge improvement in places.
I do think you need to compare the scope and ambition of the engine though. Something like Skyrim is hugely resource hungry both in gpu and cpu terms (especially cpu). It's got soo much it has to calculate. A modern fps game isn't far below with huge environments and physics to calculate plus AI etc. Some games have simplistic engines like race games where the AI needed is really just a matter of moving left or right at the correct time and wisely choosing braking and accelerating compared to most games this is very low CPU requirements. Race games are much more a test of the graphics system and how fast graphic data can be moved in than the CPU.
The PS3 is almost a two step design. Early games or less ambitious games simply use the two thread powerpc main core to run but other games make use of the six additional cell processors, some to enhance graphic performance, some to run AI, physics etc. I realise the development software itself would have evolved to make better use of the cell.
Also like the original xbox suffered from multiformat games being little enhanced over their ps2 versions the ps4 will likely suffer from its multiformat games being little enhanced over xbone. Yes we may get increased resolution or a higher frame rate or both but developers are unlikely to spend time optimising the ps4 version when they are trying to achieve parity and they struggle with xbone memory bandwidth and juggling memory around the small 32MB pool of eSRAM.
When ps3 is properly programmed it is a very impressive console but when comparing games its best to compare the same game across multiple formats. If you want to compare maximum performance of each console then yes compare exclusive games from each console. For me the ps3 is still more impressive than 360 or wii u in performance for its exclusive games. Much of this is down to the little enhancements the cell has made possible. I may think differently when I get my hands on mario kart 8 although really that game is only a graphics test rather than an indicator of cpu power. The ps3 is the complete opposite of that with its huge cpu/dsp capacity thanks to its cell processor. The wii u vs ps3 is like comparing a PC with a mid range gpu and low end cpu vs a low end gpu and mid range cpu. Both have their strengths in different areas.
