There's been much forum discontent recently over the translation of the Luke Skywalker gunner upgrade for 2.0. According to the translation he can spend his force point to rotate his ship's mobile firing arc. This mechanic has been criticized for effectively reintroducing the 360 degree turret: a ship with Luke can swivel its arc in response to where enemy ships move.
Can't higher PS turrets do this already though? Rotate arc is an action and happens in the Take Action window. If you're running Han then Luke is more of an action economy upgrade than anything else and you may be better served by another gunner card. The one that lets you shoot out of both arcs jumps to mind.