In our time with the Canon RF 24-70mm f/2.8L IS USM, it performed like an amped-up version of the EF equivalent – in particular, focus seemed snappier, thanks no doubt to the improved capabilities of the EOS R system and the faster communication enabled by the RF mount.
The Canon RF 28-70mm F2 L USM Lens is a large, heavy and expensive lens that is also awesome. Garnering a world's first on its credit list, this lens brings the f/2 aperture to the extremely useful standard zoom lens. With the RF 28-70mm F2 L Lens in your hand, it is like having a large kit of prime lenses always mounted on the camera.