I test drove the 335i, G35, G37, Acura TL, and A4. The BMW was easily the best driving car in every aspect, more refined, fluid, and precise by far. I went with the IS because of the reliability for my wife, plus she liked the interior. So far the IS has been in the shop four times for squeaks & rattles. The car handles like a Buick compared to the BMW. The suspension is harsh and the car has needless understeer, always pushing and sliding the front end beyond the intended arc. There really is no feel in the controls (steering, throttle, and brakes). If your near retirment age and want a melow driving exp this car is great. Fit and finish are great and the car does have a strong engine.
Interior materials, Sound system, nav. Great for straight away power.
Body style - looks like a Scion. Fix the rattles. Larger back seats, better gas mileage.