Heavy, slow, stiff. What about...
The steering is tight, but not abnormally so. It is not difficult to turn, but it is tighter than your normal luxury sedans, like the Lexus you currently drive.
Keep in mind that what you are used to driving is going to greatly affect your perception of it. I did not drive my Taurus all summer, just the Z. When I finally hopped back in the old beater, I literally felt unsafe. Brakes sucked, steering was loose, the car floated along with no responsiveness in anything I did. I seriously felt like something was wrong with it. Nothing was of course, I just forgot how insanely different the two cars really are.
I was playing Gran Turismo 5 with a Logitech G27 wheel and shifter for the past couple weeks, and pulled out the Z a couple days ago when we hit temps in the 60's after being freezing for weeks. Now not only did the steering and handling feel very odd compared to the Taurus, which is an automatic, but the shifting felt heavy as hell because of playing GT5 with with a little plastic shifter.
Go test drive a new one, I'm guessing it will feel pretty close to the used one you drove.