Well, just read my sig. God, how I love that moment. Not to argue with the previous poster, but I did not interpret Luke casting his lightsaber aside as defiant. It was serene. Confident. In that moment, Luke knows that he has been tested, and this time (unlike his failure at the cave from ESB) he is a Jedi. I think he finally felt the force being with him in the way Obi-Wan spoke of in SW.

That's why Luke calling out for his father, while not ruining the scene, kind of detracted from it. That scene would have worked just as well without Luke calling for his father - but I guess GL had to overexplain yet another detail.