I like it and would own one. For the same reason I would own a lotus 7 kit car with a japanese motor, or an mg tf with the same.
It is a way of getting the look you are after at a cost you can afford, and reliability, performance and handling not available on the original.
Trainspotters may not be impressed, but I'd prefer a z8 body on top of a z4 anyday over an actual z8 for day to day practicality and usability. (it'd have to be a 3.0l z4 or z4 mroadster though).
How about this, which is just barely a kit. It's basically a hand built race car (you buy the tubular space frame already welded) & then you assemble. It uses a GM 5.7l to 7.0l engine, Porsche transaxle, some parts from the C5 Corvette. Koni struts/shocks designed specifically for the car. 335s on the rear! Weighs in at 2350 lbs.
0 - 60 in under 3 sec, beats
a Ferrari Enzo, a Porsche GT, a Saleen Twin Turbo S7, Ford GT, and a Lamborghini Mucielago. 1.05 lateral G, same as the Enzo. Costs $40K - $60K to build, a lot cheaper to own and maintain than any of the other cars listed.
I've had my eye on this one for a few months now. If you want to see more, go to FactoryFive.com/gtmhome.html .