The PS3 is better on paper (though "the power of Cell" was a vast overstatement at the time), but unfortunately for developers, it's also a real pain in the ass to develop for. This isn't a problem for developers making PS3 exclusives, who can produce some outstanding visuals because the PS3 is the only hardware they have to care about. The moment you decide to go multiplatform, however, the PS3 becomes the weakest link, because developing for it is apparently very different than developing for the 360/PC, who feature very similar architecture. There's a reason most (not all) crossplatform titles end up looking better on the 360.
I could come up with a random number right now.... let's say 80... 80% of anything related to video/computer games is massively over-hyped... now I made up 80% but I am pretty sure the vast majority of stuff is still over-hyped. 360 has a more similar architecture to the PC, true, but it still varies. For example on a PC, the only graphics cards that don't have their own RAM are Integrated Graphics Cards but we can be assured that ANY such card won't be cared about why Bethesda for the PC, since those entry level chipsets would never be able to handle Skyrim. PC Architecture is more variant then any other system too, consoles are pretty similar on the inside while how many different types of PC exist... so sure, an X-Box 360 is more like a PC then a PS3, but it's not really that meaningful since you'd still have a lot of re-writing to do anyway. In the case you already had working engines tho (and this is the assumption I am going off of), if you are going cross platform, you are going to be limited by the system that can handle the least, in this case that would be the X-Box 360, the PS3 might be more complicated but it's still more powerful. Also I'd say you were wrong about most, off of the games I personally look at, however any such discussion of cross platform titles could only really be opinion but I would mention that Fallout 3 did seem to look rather noticeably better on PS3 then X-Box 360.
You're wrong on that part! The Xenos GPU outperforms the RSX any day
The Cell CPU has more firepower though...
Actually I am not wrong, because I was including both together, while I have not looked into the architecture of the two machines myself, I am lead to believe the X-Box 360 has pipelines which are shared between the CPU and Graphics Card that only one can any given pipeline at any given time, thus why I said the X-Box 360 is more dynamic then the PS3, but overall it has less processing power. I can't remember what the pipelines were too mind you, but If I remember right the Xenos GPU has no real RAM of it's own, so it's probably memory. On top of this the RSX is capable of far more gigaflops then the Xenos processor, gigaflops being a measure of floating point operations per second what is a measurement of processing power. So again, I am not wrong on this count. Processing power is not always equivalent of performance, however, anecdotally, on the majority of games (not all because the PS3 is harder to make games for due to the architecture) I tend to see slightly better graphics on a PS3 then an X-Box 360, on average.