I use mine only for very long distances. I have the 2.0 GT Line + an additional package which gives me absolutely all comfort the Stinger can offer minus the engine power and the adaptive suspension.
So far I've done about 15+ road-trips of over 2000km so I think I have a pretty good idea about the car's comfort.
DRIVING & GADGETS:
I almost always drive in comfort mode (with pre-tuned "hard" suspension). Steering is just perfect, not too heavy, not too light. Gearbox is ok, pretty smooth but sometimes a little too oriented towards fuel consumption. Suspension is good, not too hard but still able to keep the car in check.
If you like to send it, everything is just right, except for the suspension which just can't hide the almost 2 tons. Not sure if the "sport" setting of the adaptive suspension helps since I could not get it on the 2.0.
The car is pretty quiet at 140-150km/h. However, there is some tire noise if the asphalt is a little rougher (I have the 19" with Continental tires). The adaptive cruise is very nice and responsive and works even under severe weather, like heavy rain. The active lane keep is also pretty good but I don't really use it. I like to drive. However, the rain sensors are seriously lacking. This can get a little tiring after a few hours. The led headlights are really good (minus adaptive function which doesn't work on high beam) and the auto dimming of all mirrors works great!
After a 10-12h drive (Bucharest - Vienna) I can usually go out for dinner and drinks.
INTERIOR COMFORT:
Seats are super comfortable! The extension of the seat helps a lot on long trips and the ventilation works like a dream in the summer. However, I do find the seat heating function a bit too aggressive. I only use it when I start and then quickly turn it off. The AC is ok, nothing to complain. The HK sound system is good enough. The TomTom navi is almost always better than google maps, except inside cities. That is if it has access to a hotspot and can get traffic info. Both screens (7"+8") have great luminosity and even under direct sunlight you can still see what they're displaying.