The key to using Wikipedia is to think about the topic, and whether people are likely to want to be biased about the topic.
I avoid Wikipedia with regard to hot political issues such as global warming and abortion.
I use Wikipedia a great deal for science, engineering, and history.
I actually find Wikipedia to be very accurate - better than almost all newspapers - for current crises. It was a great help during the Boston Marathon bombings and Newtown, CT school massacre. I was able to learn what was going on without dealing with the drama and mis-information on the web, on TV, and even in newspapers.
Occasionally, I've been able to improve what I see on Wikipedia - a joy in its own right.
Used carefully, I think it is a great resource. And, note, my wife is a college professor who teaches students how to write research papers. She allows them to cite Wikipedia for background information as long as:
- the info is not central to their thesis
- the topic is not one that people have a lot of passion and biased views on
- the topic is not highly politicized (for example, the archaeology of Jerusalem)
- the article cites a wide range of up-to-date sources
Even if students can't often cite Wikipedia, it can be a great starting place for finding ideas and sources (in the footnotes) and for getting background on a subject.
It is a big help for me in fact-checking for my HubPages writing. And nothing I've published relying on Wikipedia has been challenged or criticized. I don't rely on it the same way when publishing articles in juried professional journals.
Wikipedia is linked to Wikimedia Commons, a great source for photos, and we can use all photos on Wikimedia Commons on HubPages.
So, if we know how to read it well and check each article's sources carefully, I find it is far more reliable than several others who answered here seem to think it is. I spend a fair amount of time on the site and use it to enrich a lot of my hubs.