Read Rusty Blackwell's comments on driving the 2008 Cadillac CTS.
I'm a bit disappointed with the CTS. The ride can be a bit bouncy when you're just cruising around on back roads, and the transmission is slow to kickdown (but quick on the upshifts).
Most of my issues are with the quality of the car, however: The passenger-side ventilated seat clicks noisily, like you pinned a baseball card in the spokes of your bicycle. The HVAC vents blow way too hard at their lowest setting, and closing off the vents doesn't completely solve the problem. The seats are too firm (as Phil said, you sit ON the seat, not IN the seat). There's also too much wind noise from the A-pillars.
Still, there's lots to like about the CTS. I really like the exterior design, and the interior has its positive points as well. I particularly love the popup nav display, which you can leave in unobtrusive mode most of the time and raise it up when you want/need to use the nav system or other functions more involved than basic audio. The CTS also handles quite well for a 3900-pound Cadillac.
The CTS is certainly a good car, better than its predecessor, but in my mind (and in spite of its attractive, sub-$40,000 price tag), it's still clearly behind its German competition.