This is sounding pretty good...
Because the 24-70 mm F/2.8 Di VC USD is a high-speed zoom lens with maximum aperture of F/2.8, its VC system must drive a lens that is larger and heavier than other zooms. Therefore, the shape, size, and layout of the drive coils are all designed to obtain sufficient thrust. The result is a full-size, high-speed zoom that provides the same high level of compensation effect.
The new lens uses a lot of high-end components in its 17-element design: three LD (low-dispersion) elements, three aspherical elements, one hybrid aspherical element, and two XR (extra refractive index) elements. That boils down to a better job handling chromatic aberration and other lens problems.
The lens also has rounded aperture blades for better out-of-focus areas. "This rounded diaphragm retains a nearly circular shape even when taken two stops down from its fully open state," Tamron said.