I had a G37 coupe before my M3 and it was a fantastic car. Is it a pure sports car, no. Is it a pure luxury car, no. It's somewhere in between. The fact that I bought mine for $36K new with Journey package, Navigation, satellite, etc, I still consider it a great value. They are pretty quick for what they are (a near luxury, heavy GT car). A lot of fun to drive and lots of creature comforts.
Its definitely no GTR and it's definitely no M3, but to say that they are bad is plain wrong. The VQ series of motors are great motors as well. The nav / computer system in it is actually one of the best ones I've ever used and I've used quite a few.
2011.5 M3 ZCP
ESS Tuning VT1-535
BBS CH-R 19x9/10.5