Weird problem, but they happen. Better than my first G4, which just didn't have a 2nd processor (that was the store I ordered it from's fault, although it's a good thing I was savy enough to notice).
And I don't think it's necessarily accurate to assume that 25% of all G5s have problems--remember that people with problems are far more likely to mention them than people without any. Besides, it's a 100% new computer--completely new motherboard, completely new processor, completely new 64 bit architecture, completely new subsystems, completely new case design idiom--so there's a few more kinks than usual to be expected. Mine works perfectly save a whiny Radeon 9800 fan, but that's not Apple's fault.
I don't think Apple has had a computer with that much new in it since the PPC line first debuted (maybe the first G3s with the new world ROMs, though the case was the same as the previous gen and I don't think the switch to G3 processors was nearly as big a jump).