Hi,
can't compare to the Coupe but I had a few other big cars (mainly BMW "the drivers car") the latest a 745i (with body-roll control). The BMW (745i) is good but the QP is just at another level! A real drivers car. You'll take the long way home! Ride is harder but not annoying. Motor is to die for and you'l be revving it much more than you should just for fun. And the sound, ah (especially with a tubi). F1 could be slightly better but I do prefer it to the BMW ZF Auto. However I do only 15% city driving and in stop and go the F1 is a bit annoying. If you do 50%+ city I would wait for the new full automatic ZF QP....
So it is much more much appealing, sporty, stunning than almost any BMW, MB, Jaguar, Audi.....
Now the "bad" things: Trunk is much smaller. Maintenance more expensive. Drinks more premium gasoline. Too few service places and that can be a bore if you make many long trips and you need assistence. If something breaks you need more days to repair it since dealers normally don't have parts in stock and they have to come over from Italy. Less electronic gadgets than a BMW (can be good also). Finally the car attracks much more attention and looks (my windows are always dirty from people peaking into the car) then I suspected.....and sometimes you don't feel ok letting it parked in a parking lot/street....
Great car, I love it and so far (30.500km) the only problems I had was a suspension sensor breaking down (warranty and I could drive the car meantime) and the keys were not as drop-proof as my BMW ones.....
Go for it! (my choice now would be Sport GT but with 19' wheels)
PS when changing I was doubting between M5 V10, S6/S8 and the QP (need 4 doors) and went for the QP. It is much more sexy and has soul. The M5 is probably the better, easier, faster, more rational choise but has less (no?) soul...The M5 is a hell of a car...the QP is a lifestyle