You don't give him enough credit. From an engineering pov alone, Friendster, myspace and twitter were often down or terribly slow.

Also, the foresight to launch a platform.

Launching news feed despite howling criticism.

Taking the company public with little investor surplus, taking heat on CNBC for a year until the market caught up to what they were doing.

Not putting ads on the site in numbers that turned off users but Having enough to run profitably from an early era

Great hiring.

Edit: Also, I think most people misunderstand the primary benefit of school-by-school rollout. By the time people without .edu addresses wanted into Facebook it was already successful. Their growth plan was premised that if you can get 50% of the people in a network to use something, the other 50% (or close to it) will pile on. You can't do that everywhere all at once across the country, let alone the world. The cliche goes... How do you eat a whale? Bite by bite.