There are pluses and minuses to using kit lenses. So don't get me wrong, they cannot substitute professional lenses. But they can do a lot.
Lens performance is looked at from a very wide range of criteria. Some can be measured, others are more a matter of taste. The key ones are (not necessarily in this order) - build, speed (or how wide the aperture opens), distortion, centre sharpness, peripheral sharpness, sharpness at different apertures, colour rendition, ability to handle flare, chromatic aberration, bokeh, image stabilisation, zoom range, filter size, smoothness of movement, focus shift, focus breathing, and many others. Also, if you have a fetish for gadget looks then add finish and feel as well to my list above. And last but not the least, price.
Here I shall limit myself to my experiences with the key criteria.