I also heard a story on this topic on NPR, about a study that found little difference in accuracy between Wikipedia and Encyclopedia Brittanica.

The British journal Nature examined a range of scientific entries on both works of reference and found few differences in accuracy.

...

"Only eight serious errors, such as misinterpretations of important concepts, were detected in the pairs of articles reviewed, four from each encyclopedia," reported Nature.

"But reviewers also found many factual errors, omissions or misleading statements: 162 and 123 in Wikipedia and Britannica, respectively."

One thing the NPR story noted that the BBC one leaves out, is that they also surveyed working scientists and asked them how often they used Wikipedia. I believe something like 17% said they used it at least once a week. Count me among that crowd.

Just as your English teacher warned you not to use the encyclopedia as the sole source (or usually not even a source at all), it's often a great entry point into a topic and a great place to look first.

And Wikipedia is much less clunky than the EB, which reminds me of an old Monty Python skit (at least how I remember it).

[a man knocks at the door]

Woman: Who is it?

Man: A burglar.

Woman: A burglar?

Man: Yes, ma'am.

Woman: Are you sure you're not an encyclopedia salesman?

Man: Oh no, ma'am. Just here to burgle some of your things, maybe club you over the head.

Woman: Oh all right. [opens door]

Man: Would you like to buy a set of encyclopedias?

So Wikipedia doesn't weight 80 lbs., and doesn't have annoying sales staff. And I'll bet Britannica doesn't have nearly this much info on Batman.