The other scenes are indeed very nice, but they have completely different feel to them. With other scenes, i feel like i'm just having a little fun with my gal pal. While that one has so much energy in it! You can almost feel, how much Sam wants it. how much she desires it. how much she NEEDS it! Keep in mind, that Sam has far more sexual experience than Ari, and probably had her fair share of orgasms before. And for her to have such an earth shattering orgasm, from someone as inexperienced as Ari... Poor Sam was probably dreaming about this for quite some time.
Or, it all may be just my wild imagination