The GranTurismo is in an entirely different category than an M3. Maybe Maserati should be more obvious that it's a grand touring car... like putting something in the car's name?
I have a soft spot for the GranTurismo. Sexy curvy hips, great interior and awesome sound stock. That said, it's huge and heavy - it drives well for a DD but, again, it's no where near the performance and handling of the M3.