Florian: I see in your signature that you do not longer have the Tamron 24-70/2.8. Is it so and if so, why? No good?
Overall I was satisfied with the Tamron, but I also got a 17-40 now which is a more likeable lens for a hike or something because of the extra milimeters at the bottom. For portait I use 100L or 135L when I can and I always try to. I did not mount the Tamron that often and when I did, I used it mainly in lower focal ranges, I almost never use anything between 50 and 70mm.
Anyway, I am waiting for the new 50mm IS and when this releases, I would have sold the Tamron anyway. I got a 35mm IS for now and that is smaller, lighter and faster than the Tamron so it's probably going to be my hand-held-walkaround lens until or if an affordable 50 IS drops.