I bought these tires to replace the factory Hankook death-traps that Hyundai had put on the car after I almost died getting to the store in the MILD slush. I immediately noticed an improvement while driving in the same nasty weather on the way home. The one thing I really noticed is how these tires HOWL while driving in the ice and snow. They also will sing a little if the temp is in the 30s or below.
Another immediate thing that I noticed is that the fuel economy for my wife's Elantra went from a more varying average of 33 mpg to to a pretty much consistent 28.5 mpg.
The tires ride a lot smoother and the car does not do the pothole two-step that it used to do but if you go hard in to a corner it is evident that turn in is not as crisp.
One more thing that I will note is that the pressure in the Ecopias are set at 32 psi while the Hankooks I used to run were kept at 35-38 max psi, though there was never any noticeable differece in the ride for the Hankook's in the variation from normal 32 to my running psi.