Jeremy Clarkson, of Top Gear fame, has not been a fan of the new hard top convertibles from BMW (see his review of the 335i convertible last year) and he is consistent has he trashes the new M3 cabrio.
From Times Online: "I like the new M3. As a coupé... The saloon version is even better. It doesn’t have a carbon fibre roof, which makes no difference at all, but it does have four doors and a bigger boot, which means your children can come too. And it’s a little bit cheaper.
"The new convertible version, however, has a problem. Taking the roof off, say, a Peugeot doesn’t really matter. Who cares if it’s all floppy as a result. It was never built to be the ultimate driving machine in the first place.
"The problem is that BMW’s M cars are built to be the last word in precision, handling, fun, grip and speed. And if you take the roof off, you are sacrificing torsional rigidity, which means you are sacrificing precision, handling, fun, grip and speed. You are therefore removing the whole point of the car. It’s much the same story with the Porsche 911." more.