How accurate is Wikipedia?

John Siegenthaler has a real beef with Wikipedia:

This is a highly personal story about Internet character assassination. It could be your story.

I have no idea whose sick mind conceived the false, malicious "biography" that appeared under my name for 132 days on Wikipedia, the popular, online, free encyclopedia whose authors are unknown and virtually untraceable. There was more:

"John Seigenthaler moved to the Soviet Union in 1971, and returned to the United States in 1984," Wikipedia said. "He started one of the country's largest public relations firms shortly thereafter."

I looked up one article which I know something about: the biography of Bessie Coleman. I found it illiterate, full of mistatements, so I rewrote it. I have no idea whether my changes have survived. My concern is that some student will mistakenlyh use this biography as a source, thus passing on errors and ommissions.

You can understand why librarians do not hold Wikipedia in high esteem and would prefer more authoratitive sources.