What effect does seeing Lenina have on John and why?

John falls in love with Lenina when she comes to the Savage Reservation because he has never seen anyone who looks likes her. Huxley shows more than a hint of racism when he writes,

He had seen, for the first time in his life, the face of a girl whose cheeks were not the colour of chocolate or dogskin, whose hair was auburn . . .

He also likes her because she looks at him with "benevolent interest" and because she is young, plump, and pretty and has smooth skin. He wants to go to the World State partially because of her. He thinks of Lenina as

an angel in bottle-green viscose, lustrous with youth and skin food, plump, benevolently smiling.

Lenina's loveliness causes him to think of Miranda in Shakespeare's The Tempest seeing young men for the first time. He has a similar response to Lenina, thinking, "O brave new world . . ."
He has a moment of fear, growing pale because he thinks Bernard might be married to Lenina, but he is reassured that this is certainly not the case. We can see the culture clash coming, however: John has no concept of the sexual mores in the World State, having grown up in a more old-fashioned cultural environment.