In sumary...
- CPU @ 1.25Ghz (not idle clock); Tri-core PowerPC 750; 1 thread per core; OO design; shorter pipeline; better IPC; weak SIMD;
- GPU @ 550Mhz
For a PowerPC 750 the clock is fine (that's almost the max clock the 750 can run) and it's almost 2x the CPU clock of the Wii (@730Mhz).
It's a CPU way slower than 360 CPU and PS3 CPU.