I know this is a BMW site but some of the comments are not quite in my reasoning but I guess thats why they have apples, oranges and bananas etc.. I have been a AMG man myself but got tired of how crappy MB service has been here so I decided to give BMW a try. I just this week picked up a lease turn in 2008-M3-cabrio-6sp-Space Gray with only 24k on the clock. With it being driven by a lady and being turn into a CPO car also you cant go wrong I think.
Pros: I love the comfort/luxury the car has and it seems to be a pretty decent daily driver so far. It is also pretty squeak and rattle free for a convertible.
Cons: is I wish it had more low end tq. This would be better for launching the car off the line and help with driving in stop and go traffic.
That being said the best handling fastest "stock" car I have owned has bar none, hands down been the GTR. After a year or two I will probably get another one. I only had a cobb tune with mid pipes and exhaust and it was a beast. My only pet peeve would be the spartan interior. It could be a bit more luxurious and have better quality materials used but other than that it was a great ride. The service scare that circulated around the web was totally false as was the glass transmissions too. What made that car so great was the combination of 4 things = AWD+Dual Clutch transmission+electronics and of course the 3.8 liter twin turbo V6. If you can afford one get it.