In scene 5 we see Ophelia's madness, so we can assume that the commitment to revenge damages those around the actors (since Hamlet drove her mad through killing her father).
At the same time, though, Laertes' commitment to revenge seems to act like a tonic (of sorts) on his soul, focusing him sharply on what he needs to do to revenge his father. He had been a kinder sort before this; now all that seems stripped away, so he's revenge and little more. In a way it matures him. He's willing to do whatever is necessary to take revenge. In this he's an alternative to Hamlet, who (in other scenes) shows how revenge can cause someone to lose focus.