Yeah...all the greatness of the 1st time goes away, but it depends on who's playing it, some people play games quitely in a candle-lit room with the volume up high, trying to pick up new things they didn't pick up the 1st time they played it but still enjoying the moments. Legendary games never loose their greatness

Metal Gear Solid 1
Zelda: Ocarina of Time
FFX/X-2
FFVIII
Gran Turismo2/4
Super Mario Bros.
Animal Crossing
Street Fighter(Most of them =D)
Woooooooh! I could go on forever