The Tamron 70-210mm F4 is a great telephoto lens option with relatively few shortcomings considering its reasonable price point. Its optical performance should represent a meaningful upgrade for those using entry-level 55-200mm or 55-250mm kit zooms, and the F4 aperture saves weight and expense...
DSLR users looking to upgrade their kit telephoto zooms and those wanting to photograph moving subjects in good light; portrait shooters and outdoor events
Those shooting in dim environments and need a wider aperture; those shooting on the highest megapixel bodies and need the best sharpness they can get