product quality: for weight reduction body is made out of plastic (but seems to be solid), lens connection is made out of metal with a rubber lip, zoom is very good, focus ring is excellent, the lens has a fixed filter holder, stray-light protection is only streaky, AF is a little bit faster than the AF in version one
optics: very high performance, you can use it with open aperture, yout get top values if you set the aperture to f/4, at APS-C the resolution is a little bit lower, visible vignetting at 24 mm (even if you go to f/4) on FF, lower visible vignetting at 24 mm (even if you go to f/4) on APS-C, visible distortion at 24 mm
Vignetting in stops:
24 mm on APS-C, aperture 2,8/5,6: -0,83/-0,60 / Tamron -0,66 / -0,52
40 mm on APS-C, aperture 2,8/5,6: -0,56/-0,35 / Tamron -0,56 / -0,35
70 mm on APS-C, aperture 2,8/5,6: -0,64/-0,23 / Tamron - 0,52 / -0,24
24 mm on FF, aperture 2,8/5,6: -1,91/-1,33 / Tamron -2,31 / -1,33
40 mm on FF, aperture 2,8/5,6: -1,58/-0,96 / Tamron -1,73 / -0,95
70 mm on FF, aperture 2,8/5,6: -1,52/-0,77 / Tamron -1,97 / -1,15
24 mm on APS-C/FF: -1,6% / -2,3 % (barrel-shaped) / Tamron -1,9 % / -3,1 % (barrel-shaped)
40 mm on APS-C/FF: 0,1 % / 0,4 % (pulvinated) / Tamron -0,1 % / 0,3 % (barrel-shaped/pulvinated)
70 mm on APS-C/FF: 0,4 % / 1,0 % (pulvinated) / Tamron 0,4 % / 1,1 % (pulvinated)
overall efficiency in percent on FF (aperture 2.8/4.0/5.6/8.0/11)
24 mm 83/92/87/85/83 - Tamron 80/82/82/81/78
40 mm 78/82/82/81/82 - Tamron 75/82/82/81/79
70 mm 82/82/85/83/82 - Tamron 74/77/78/78/81
Stars from small light sources at f/16 or f/22 in low light if you shoot landscapes
The nine blades produces 18 star spouds. I don´t like such stars. With the old lens with eight blades you get stars with eight spouds. It´s a optical fact, that you get with an uneven amount of blades the double amount of star spouds as you have blades.
The EF 24-70 2.8 II is the best zoom lens in this focal range. It´s better in optics than the Tamron (Tamron has more vignetting on FF) and the AF is much faster than the Tamron AF. I don´t like the rotating direction of the zoom ring from Tamron. It drives me crazy, because it´s reverse to the Canon zoom ring direction. I like the lens hood from the version one. If you shoot into the direct sunlight with version two you have to shade the lens opening with the new hood on it with your hand or a black piece of paper or you get sunspots in your image.
I don´t put the data from the Nikkor 24-70 made with the D800E on the net, because the optical quality is far away from the EF 24-70 II. For D800E and D4 users I hope, that Nikon put a new version on the market.
If it´s worth the price for you (around 1.000 more) you have to decide for yourself. I have to work less than a day as a professional photographer for it and I can say definetely YES to the lens.
I hold the prototype and the production version as my everyday walk-around-lens for portraits, sports, events and landscapes (private use and travelling) in combination with the 16-35 2.8 II and the EF 70-200 2.8 II IS.
For business I mostly prefer the primes from Canon and Zeiss and my Hasselblad. But the lens and the EF 70-200 2.8 II IS is a great performer for business to.