The difference between EF17-40 & Tamron19-35

If somebody have used these lenses. Could they share practical experience with this lenses. I know it will be unfair to compare these lenses due to huge price difference.

at least I can tell you the 17-40 even sharper then 16-35.

I've used them both.
The tamron was ok, it has a non rotating front element which is good for polarisers and sharpness isn't bad considering the price. It lacks some contrast though...
But the build quality, handling and sharpness fof the 17-40 is something else completely when comparing the two.
My take on it is that I would not enjoy using the tamron every day but the 17-40 I could. Plus you can put the hood of a 24mm F1.4 on the 17-40 and get better shading for 1.6 crop.