Wikipedia has come under increasing criticism lately, for instance read here. The core problem is simple: for most entries, anyone can write anything. How can you trust the results? For that matter, what does the Nash equilibrium look like?
But this critique misses the comparative advantage of Wikipedia. Entries tend to be link-rich, and the ongoing debate and revisions refresh and improve the links. Think of Wikipedia as hiring someone to do search engine work for you, not just Google but the other brands as well. They then report back with the best links. Wikipedia brings you this service for free.
In turn Wikipedia writers receive the satisfaction of being read and of participating in the grand endeavor.
If you unconditionally trust controversial assertions in Wikipedia, you need to be much more careful. But if you think of the service as an exchange of sorts, and understand what you are getting, Wikipedia is a remarkable benefit.
Read Clay Shirky as well; he notes that while Britannica gets worse over time (ever read an old edition?), Wikipedia gets better over time.