I think it's funny how some people are so defensive over an M3 that they go nuts when there's any other car that beats it.
Since someone asked- I bought the M3 because it's an amazing machine. It's fun to drive, handles well, pretty quick and has all the creature comforts. And you can fit 2 people in the back seat. I thought this is what I wanted, but in the last 8 years, I've gone through 27 different vehicles. I like to experience everything, so the M3 was a step. Who knows, the Z06 may be as well or it may be a keeper!
I bought a Z06 because it has many more things that the M3 can't offer. I don't care what brand a car is, I'm looking for a car that looks amazing, is stupid fast (and I'll make it even faster) and handles like its on rails. Interior is fine on the Z06 too- like someone posted earlier, the 3LZ (or 4LT) comes with leather stitched interior. The Z06 does have nice interior, not the best, but nor is the M3. I also like being able to modify the car and not pay an arm and a leg. Hence why I didn't stick with the M3 or switch to a Porsche (although a 997 Turbo gets my vote any day).
As far as spending $120k on a vette being stupid, it's not any worse than spending $120k on any other car. $120k on a car is never in any sense considered 'smart'. But- we're all car buffs here (at least I hope so and not just buying these cars to show-off, which I'm starting to wonder about) so we spend money on what we like and enjoy. Different strokes for different folks.
All that being said- the Z06 is a car that any true car enthusiast should definitely own at some point in their life (if possible) or at least drive one. You have to "drive" the car and when you do, it'll never disappoint.