Got a great deal on a leftover new Super ($31.7k out the door) when my '07 DTS was pulled ahead by GM. Ride has softened somewhat with break-in, but the magnetic ride control is still firmer than in my DTS. Knew I would have to replace the standard Bridgestone tires in order to make the ride acceptable. Replaced tires with Goodyear Assurance Comfortreds (235/55/18) which adds about 1/2 inch to the tires diameter and about 1/4 inch to the car's ride height. The tires made a big difference when compared to the hard riding and noisy Bridgestones. The car, at 2,600 miles, gets about 18 mpg combined vs. 20 mpg with the DTS. This may be due to the performance tuning and the final drive ratio.
Traded a 96 Caddy for this in May. After driving a few days, found that the transmission whines loudly in the 15- 30 MPH range. This is the 4T80E transverse transmission which only comes with the 292 on the Super and the Cadillac DTS. GM has a bulletin out on this but a design change projected for early August did not come through. Totally unsatisfactory. GM knew about this way back in 2007 but didn't tell anybody. All other aspects of the car are really good except, as noted below and disappointing MPG. My Caddy got over 30 MPG on flat land and this only gets 25. My 1984 Olds 98 still gets 27. I guess that's progress for you.
Have driven Cadillacs for over 27 yrs, my last being a 2001 DHS. First Buick ever. My Buick Super is giving me excellent performance. No wind noise. Fuel economy is what is to be expected with a 292 HP Northstar engine, (20mpg city driving) and absolutely fun to drive. A great many options comes with this vehicle. I've also saved several thousand by buying the Buick over the Cadillac with just about all the same options. Completely satisified