I test drove one about a month ago, before I changed my mind about getting a new car. No V8 at that time, so I test drove a V6 with tech package. I was favorably impressed with the ride and power. Extremely competent but not quite the "sport" feel. But definitely luxury. No doubt about that. Maybe the V8 will feel more sport.
I didn't get a chance to hit any rough pavement, or a twisty one at that, but I get a feeling that most luxury car drivers don't hit one of those on a regular basis anyway. So I can neither confirm or deny magazines reviews on this car's behaviors on rough/twisty roads.
Interior feel is, like I said, straight lux. The leather accent on the dash looks and feels very nice. The i-Drive-like navigation knob feels weighty and big in your hand and I had no problem using it.
If I were still in the market, this car would've been one of top three candidates.