Sharpness is dramatically improved, flare reduced, improved color, and IS added.

However I think it renders a richer color than the zoom and is much smaller and lighter.

It is very sharp with great color reproduction and very light weight

well I was not impressed with the findings , color flare was too noticeable , close up shots had good center focal but was to narrow with blur to close to center ,color was not accurate with flash could not get Hi Res shots with this lens

and I feel like this lens produces better color

This newer version is sharper with better contrast and color at all apertures in all areas of the field on a full frame camera.

In fact, in some ways it exceeds them in terms of being much less prone to flare than either of the more expensive L lenses