Took the Tamron 24-70 f/2.8 VC out for a test run past few days. Didn't really test the lens to its limits but some thoughts:
~ AF isn't as fast as the Canon or Nikon equivalent, but then again price isn't the same as well, so can't compare.
~ The VC (Vibration Compensation) is stated as up to 3 stops, which I think is pretty optimistic. Probably closer to 2 stops to be honest.
~ Weight-wise, lighter than the Canon 24-70 Mk1 but slightly heavier than the Mk.2 which is just released.
~ I don't like the way the lens zooms. To zoom in, you need to turn the zoom ring to your RIGHT, which feels odd to me despite me coming from Nikon. Maybe cos with Nikon I have mostly shot with primes except for a Tokina 12-24 which never really saw much use past 13mm.
~ At f/2.8 it's a little bit soft if pixel peeping, but on the whole, acceptable.
Other than the above "quirks", the lens is decent for what I paid.
Some shots taken with the 24-70. No post processing except crop or resize to 800 X 533 pixels.