Is Facebook Growing Up Too Fast?

Sometime this week, this five-year-old start-up, born in a dorm room at Harvard, expects to register its 200 millionth user. (Click to enlarge.)
This staggering growth rate — doubling in size in just eight months — suggests Facebook is rapidly becoming the Web’s dominant social ecosystem and an essential personal and business networking tool in much of the wired world.Do you use it?If not,why not?