My G37s 6MT Coupe was a great car. Not everyone is looking for something that is track ready. It was a comfortable drive, offered sport features and looks, and the price was unbeatable in that market. The lease rates are really good on them as well. It is in the same price range as a 328. I'd way rather have the G than a 328. A 335 is significantly more expensive than the G similarly equipped.
The rear seats were usable for short trips, but nothing more than that. The trunk was relatively small too... because it has a spare tire.
I thought it was nice that they added a lot of the cool sport features (19" wheels, sport brakes, contrast stitching, etc.) standard.
Given the M3 is a much better car, but let's be honest it's almost twice the price. My G Coupe was $40K MSRP and my M was $72K MSRP. That's not even close.