Coilovers

Who here has coilovers on their car? I am curious as to how coilovers affect ride and handling. I only want to lower my car about 1.5," but it would be kind of cool to drop it 4" if I wanted to. I saw an ad for a new Koni coilover kit, anyone know if its any good? What about Ground Control? I want better handling, but I don't want a terribly rough ride. I can give up some comfort, but I would like to keep my fillings intact. Thanks!!