What Tamron got right with this lens:
Vibration Compensation. At time of writing, it’s the first and only 24-70 to have it, and it makes this the most useful 24-70 on the market. This may make its downsides moot, since most have workarounds.
Despite being the most useful, it’s also the least expensive 24-70.
Full-time autofocus override. No pro-grade lens should be without it.
A degree of water resistance thanks to rubber seals inside and out.
Sharp optics. Outstanding level of detail even with the most revealing of cameras. Excellent portrait lens.
Constant aperture of F/2.8.
Compact, and fits well in even small bags.
It’s a great looking lens, with some nice looking details.
Room for improvement
82mm filter thread carries a cost implication, especially if your other lenses peak at 77mm.
Large diameter and weight affects handling for those with small hands. This is my biggest issue with the lens, but it’s due to the presence of VC (see above).
Vignetting is pronounced.
Telescoping barrel doesn’t inspire confidence in the rain, even though internal seals should keep most moisture out. Other marques put the lens hood on the outside to help with this.
Bokeh is good, but not quite as smooth as the 70-200, even at 70mm.