Ophelia tells Hamlet that he is "as good as a chorus" (3.2.269). A Chorus tells the story but offers no interior insight to motivation, nor is the Chorus ever the protagonist of a play. With these things in mind, how might Ophelia's remark be interpreted as an admonition of Hamlet?
Perhaps it's an admonition from a hurt girl who realizes that Hamlet is up to something, but he's unwilling to let her in on what's going on. Ophelia's saying that Hamlet is as good as a Chorus sounds to me like she's saying, "Great, thanks for letting me know the bare minimum to this storyline...but we used to be close - why won't you tell me what's going on?"
I think this line is an admonition of Hamlet- she's basically saying that he's weak, that he's not meant to be a leader, possibly because he's a coward. She's telling him that he likes to talk, but he doesn't say anything. She's almost telling him that he can be as angry as he wants at his mother and his step father/uncle but that he'll never be capable of being king. In just a few words she delivers a phenomenal insult.