I think Hall is a bit overrated. From a points point of view, hes a top 5 LW. From a overall game/package point of view, I dont think he is.
Hes great 5 on 5. He makes some real bonehead plays with the puck at times. Hes a turnover machine (granted some of its the lack of oilers defense transitioning the puck properly). When you watch him play, he tries to do much himself, making plays that just dont work. The oilers failed in surrounding him with enough quality veterans when he and the other young players entered the league. But he puts up points, and thats what players are paid for.
Whether he is overated or not, the Oilers still lost the trade value wise. I think they had to trade one of the 3 to get a defenseman. Whether they picked the right defenseman to trade for Hall remains to be seen at this point.