No, its not a false statement. The reason being is that developers have NOT had a chance to fully utilize the 360's advanced chipset. Pointing out games like Oblivion comparisons on a very high end PC shows nothing, because the developement for this architecture is VERY new. ****, the direct L2 cache instruction handling has yet to be exploited, the environmental dynimc via the graphics GPU and its procedural synthesis has barely been exploited (a small amount via Oblivion), the streaming object and texture between the GPU, memory and CPU (for lack of better word as I've forgot what its called), and a host of others. So, NO, its imposible to say they are more powerful and be all accounts, the technical specs on the hardware IS more powerful on the 360 (unless you want to include parallel computing), its just software designers know how to eak a computer for all its worth as the instuction set at its very basic core has changed very little. The instruction sets for the 360 is very different and with multi cores and direct instruction writing to the L2, it makes programming a nightmare for ALL next generation consoles with maybe the exception of the Wii.
