The Canon EF 35mm f/1.4L II USM Lens Review page is loaded with my expectations for this lens along with comparison charts and other information.
Canon's MTF chart foretells exceptional optical performance. An MTF comparison between the version I and II lenses is included in the preview.
The image accompanying this post shows an approximate size comparison between the older Canon EF 35mm f/1.4L USM Lens (on the right) and the new 35 L II. Obviously, the new lens is modestly larger.
B&H has the Canon EF 35mm f/1.4L II Lens available for preorder.