I bought the model with the Canon EF mount to use with my 5D Mark III body. The lens is tack sharp wide open and focuses quickly and quietly with the center AF point. Unfortunately, in my tests using a tripod and shutter delay, shots that are recorded as in focus on the camera using a peripheral AF point are soft throughout. After noting this I found other reviews and forum comments with this same complaint.Tamron evidently needs to update the firmware to communicate better with the 5D Mark III (and perhaps other bodies as well). If all I wanted was to use the center point this lens would be great, especially with stabilization, but that's not what I wanted and I returned the lens. 

Question: How is the lens?
Answer: The lens tack sharp