The GPU is much more efficient and modern in it's feature set, there is more to a GPU than just flops. The WiiU's memory bandwidth is also completely built around it's eDRAM so the main system RAM isn't really an issue. We have never once heard developers complain about it's RAM bandwidth.
Actually, eDram BW might not be sufficient to support 360 levels of transparent overdrawn (particularly with MSAA), but as MSAA isn't really in use so much any more, and as PS3 sets the low bar for render target BW, that's more of a interesting thing to note than a real problem for the WiiU relative to its performance level.
eDram is used differently in WiiU to 360, so quantities aren't directly comparable, although they do seem to favour the WiiU.
The people on the other side of the argument are just as bad tbh, they fail to take into account that WiiU with its "shit" SDK's, tools and documentation, rushed development with tiny C tier / mobile development teams / tiny budgets was running 6th generation PS360 third party games like Assassin's Creed III, Blops II almost at parity on day one.
Seven years after the 360 launched 'almost parity' is not remotely impressive. Seven years is an eternity, especially given the radical advances in GPU technology and process that Nintendo had easy access to. 45nm (and a rather large 45 nm at that) is lots of nanometres. And that means not a lot of shaders.
People seem to think WiiU won't ever produce anything better than what we saw at launch yet all you ever hear from PS4/Xbone owners / fans is "Infamous and Killzone are just year one games, just wait until year three and four !!!" ect.
I don't think anyone here thinks this. There's isn't the power leap to learn your way into though (which PS360 had at introduction and PS4Bone has now), and WiiU has missed the best bits of the compute revolution. Wii U isn't a strong position to see big lifetime gains. Nintendo have a long way to go in terms of HD production though, now they're putting their back into it, and so 1st party stuff that already looks nice will continue to looks better and better.
The point for multiplatforms though is that where the WiiU is weaker than PS360, it will always be weaker, and if developers wring every last drop from those systems there will always be difficulties to face up to. Or there would be, if anyone was making games for WiiU still.
Nintendo's focus on multiplatform titles at launch highlighted their lack of hardware progress, and kinda backfired for them.
I think Watch Dogs might be the best comparison when it releases later this year when looking at the differences between PS360, WiiU and PS4/Xbone multiplatform games.
I think WiiU Watch Dogs is very like to be, or have been, binned. If Wi U doesn't see a sustained uptick in sales and 3rd party sales in the immediate future expect to see it waving goodbye from the jaws of a garbage truck.