You will get better handling, and perhaps looks too depending on who is looking. Do note that your car will be lower than original (hardly noticeable) because overall diameter is smaller and your actual speed will be lower than your speedo. At 70 kmh on speedo, you're actually doing 69.13 .. which is good because you can be doing 110 and you're actually only doing 108 kmh (the higher the speed, the higher the margin)
http://www.carbibles.com/tyre_bible_pg4.html