The-Digital-Picture has completed their review of the brand new Canon EF 24-105mm f/4L IS II. It looks like it's a lens with some improvements over the original, such as improved IS, build quality and flare reduction.
However, do not expect it to have the same great sharpness that recent Canon zooms have shown. Afterall, this is a $1099 lens from Canon. I get the feeling that it's a good upgrade, but not a great one like the EF 16-35mm f/2.8L III.
From TDP
No, it doesn't have perfect image quality, but the Canon EF 24-105mm f/4L IS II USM Lens is one of the best general purpose lenses available. It has an extremely useful range of focal lengths in a very-well constructed body that is ready for professional-duty use. It is nicely sized and has a weight that will not quickly wear you down. And, the excellent image stabilization system will make a dramatic difference in some low light situations. The fast, accurate and quiet AF system will not let you down, the overall lens design will delight and the price is not terribly high. As the 24-105 L I fades into history, this is the lens that will take its place. Read the full review
Canon EF 24-105mm f/4L IS II: B&H Photo | Amazon | Adorama | Canon Store | Midwest Photo