The 70-200mm provides a very useful range of focal lengths, either in FX format (full frame 35mm – 24mm x 36mm) or DX format (reduced digital sensor size – approx 2/3 of a standard 35mm neg). In DX, the “effective” (full-frame equivalent) focal length is about 105-300mm.
I use mine all the time for sports action, theatrical performance photography, general news assignments, and even landscapes. It has nice "reach" but is hand-holdable in most circumstances.
The drawback with fast lenses (f/2.8) of this type is that they are fairly large and heavy. My Nikon 70-200mm, for example, is 87mm (about 3.5”) in diameter and 215mm (about 8.6”) long. Its lens shade adds another 3.25” to the length. The weight is about 50 ounces – just over 3 lbs.
Of course, specs will differ from one manufacturer to another. I don’t have data on the Tamron.
G.