The truth is, Stephen Hill is a boom or bust player. He is a deep threat for the New York Jets, averaging over 17 yards per catch. In some games, like in Week 3, Hill will have huge days with over 100 yards receiving and a touchdown. In other games, he will be shut down. Because of that, Hill is both playable and not a reliable starter. However, he may be useful in certain situations.
Hill is available in most leagues right now and is certainly worth picking up to stash at the end of your bench. He is the most fantasy-relevant wide receiver for Geno Smith. Hill does not have great hands, but he is super athletic and a big target.
Young quarterbacks benefit greatly from having weapons like that, so Hill should get a fair amount of targets from Smith. He will get better as the season goes on as his routes, hands and quarterback all improve.
For this week, Hill is not a certain starter, but if you have a lot of starters with byes, he can be a reasonable flex. The Tennesse Titans are not the easiest matchup (they are ranked 11th this year against opposing receivers), but they are not a top defense either. Hill should get some opportunities this week and could be a worthy starter.
Remember though, Hill is a boom or bust player. Chances are he either gets over 10 points, or less than five. Sometimes, that is exactly what a fantasy team needs to succeed.