Sandy T:
more people buy these cars on looks and image than on ability alone.
The 458 Italia has both while the M12C no matter how phenomenal it performs 'only' has the latter.
The 360 and F430 had no problems selling despite not being in the same dimension as the Gallardo visually. The major factor is actually the strength of the brand - the level of success this car achieves will be a measure of just how much cachet the McLaren name has to the average customer.
Anyway, for my part, I actually think the MP4-12C is more attractive than the 458. There's the old adage about waiting until you see a car in person before making your mind up, but right now, to my eye, the Ferrari is an awkward, non-cohesive mishmash of styles. Some of the details, such as the headlights and triple exhaust, are downright crass. The McLaren's styling may not be at all innovative, but by keeping things simple they've produced a far nicer car in my opinion.