The price of this lens is currently too high and for me that's the only negative. For landscape usually start aperture is f/8 with tripod. For events f/2.8 is better, but now f/4 may be sufficient when is the picture quality on ISO 25600 at the same level as in the past to ISO 1600!
Nikon lenses are usually more expensive and usually optically inferior. Canon 24-105/4 (although better than the Nikon 24-120/4) is not good enough at f/4. If the new lens be outstanding from f/4 to f/11 it's enough to invest in it, especially if the high price go down after some time. Also outstanding Canon ef 70-200/4 L IS with this lens would be a great combination for high-quality photos and with these two lenses no one will miss the extra range on Canon ef 24-70/4 L hIS to the old 105mm which is just a solid combination with 100-400. New lens also likely to be much less distortion and chromatic aberrations than the 24-105. Macro ability is certainly welcome and hybrid IS also, like light weight and compact size. This lens will definitely determine its quality, and the biggest drawback is too high a price.