Marc Alhadeff reviewed the new Sony 70-200 f/4 II and compared it to the older Sony f/4, the Sony f/2.8 II and the Tamron 70-180mm f/2.8

TL;DR: The Sony f/4 II is excellent but expensive compared to the competition: the Tamron 70-180mm is sharper and 50% cheaper while being as light and compact, but its AF is not as quick as the Sony which does not suits it for sports.